My bedroom slide on our recently purchased '07 Dolphin 6320 with 20,000 miles quit working halfway retracted. Upon examination I found the cover plate on the gear housing had shattered into three pieces and some small shards. One can't purchase the gear case, or parts therefrom, so I had to replace the entire motor assembly ($755), and it was NOT easy to find, new, or used. (You will need the Part Number (P/N) shown on the sticker on the motor housing.
Diagnosing the cause, I found, and corrected the following: First, an issue, which may apply only to this year & model coach, is that only three of the four main mounting ears on the 1/4 " thick slide mechanism are attached to the floor. The fourth hangs over the plastic intake duct for the AC unit in the below compartment. This lack of being secured resulted in some twisting of entire 1/4" steel slide mechanism, lifting the unsecured "ear" about 3/16th" above the top surface of the floor.
To remedy this, I first cut away the small section of the lip of the AC duct which was directly under the dangling ear, using a Dremel tool, hammer and chisel, razor knife, and a plethora of magic words which I cannot repeat - here. There was ample space on the outer bottom floor to add a fourth hole, when drilled adjacent to the "dangling" ear, and into the back, outer edge of the 1/4" thick steel mounting plate. The under-surface of the floor in this area is plywood, coated with a type of black sealant, and is very difficult to reach without a combination of ratchet extensions - particularly if one is "height challenged", such as myself.
I purchased a standard, grade two, 3/16" X 2 1/2" bolt and washer, but rather than a standard 3/16" nut, I bought a 3/16" "blind nut" (?), which has four sharp teeth around the perimeter of a built in washer. The teeth lock into the plywood as the bolt is tightened, allowing it to be installed without needing a wrench or socket. Something similar to this was used by the factory on the other three mounting positions.
The outside diameter of the internally threaded shaft of the blind nut is a bit larger than 3/16" in diameter, so I drilled the hole just slightly larger than the shaft. With the nut taped to the end of the total combination of all my socket extensions, I held it in place, while my wife slowly twisted the bolt head, while jamming her body under the bed (a far more difficult job, but much cleaner). Once the bolt began to thread into the nut, I struck the end of the bottom socket extension with a hammer, thereby sinking the locking teeth at least partially into the plywood, holding it securely enough to be slowly and carefully tightened. If the teeth grab hold well, you're in good shape. If they don't, you'll need to hammer it in a bit harder, and deeper. When torqued down, this actually straightened out the twist in the slide mechanism!
The remaining three Phillips head machine screws were found to be loose, and I tightened them down with an impact screwdriver. The four smaller nuts at the ends of the mechanism were all tight, but obviously should be checked.
Second, the original slide motor's four mounting bolts were loose, and one had backed out about 1/4".
When the new motor arrived, I checked the eight small bolts that secure the gear case cover to the gear case. ALL were little more than finger tight! There is a rubber gasket between the case and the cover, but the gear case contains no gear fluid - only solid grease. Also, there are formations on the inside surface of the cover, that contain very small needle bearings, and support the shafts upon which the gears are mounted. DO NOT remove the cover, as you are bound to have at least some of the bearings fall out of place and virtually disappear before your eyes.
I tightened down the cover bolts, using a criss-cross pattern, bringing it down evenly around it's perimeter until each bolt was very snug.
3. NOTE: The new slide motor does not come with the four mounting bolts, which are designed to be "self locking" - IF, properly torqued, and not overly stressed. Installing the new motor is straight forward, except for the bottom bolt closest to the foot of the bed. The external shaft with it's connecting attachment block your access to that one. A short handled 1/2" box end wrench worked for me, but you only gain a small amount with each twist of the wrench. ALSO, and possibly very important, I used blue Locktite on each of these four bolts, for just a bit of extra protection from them working loose again.
I failed to note that there are three thin sheets of plywood screwed down into place over the center, and over each bank of drawers. These must be removed and set aside out of the way, to gain access to the slide mechanism and related parts. Also of note, this particular slide motor is equipped with a pinned-on fitting that accepts a socket wrench. Theoretically, this allows one to extend and retract the slide with a large ratchet, should the motor fail.
Problem is, it's mounted on the wrong end of the motor shaft, and cannot be accessed. To move it to the other, accessible, end of the shaft, one must drive out the lock pin with a drift punch. The piece is basically like a short piece of thick walled metal tubing with a nut moulded onto one end. It will fit on the other end of the shaft, but not very deeply. It may work this way, but I drilled another mounting hole in it allowing me to bottom it out on the shaft, thereby making it less wobbly.
Another tip I learned almost too late: Laying a piece of 1/2" or thicker plywood across the framework of the bed will keep you from falling into the center compartment, and with a folded up towel or blanket over the top of it, you avoid many of the bruises to your chest and ribs you will otherwise incur
At one point of position, this "cranking nut" can only be accessed by removing the second drawer from the foot of the bed. AND, it takes a good amount of torque with a ratchet to twist that nut! It will require about a one foot socket extension. Placing a short length of "2x4" lumber directly under the ratchet head will make it a little easier to twist.
I would HIGHLY recommend anyone with this MH, or any other with a single-channel bedroom slide, take the time to expose the slide mechanism, and if needed, make the modification I described, before your motor literally blows up the gear case. Even if yours has all the proper mounting bolts, I would still tighten every one of them, including those on the gear case. Plus, to lubricate the slide, you have to remove the center plywood panel to reach it anyway. "Happy Wrenching"!