I believe the block you're referring to is part of the "equalizer cylinder". Essentially it's a device for equalizing the hydraulic pressure to the front and rear cylinders that move the slide in and out. Without it the front cylinder would pressurize and move quicker than the rear causing the front of the slide to extend or retract quicker than the rear.
If it's possible clean the fluid off the suspected area and spray it with talcum powder or something similar to identify exactly where the leak is. We had a leak at the same spot in our 2001 Adventurer. It turned out to be where the end of the hose was swaged to the fitting. It's a lot easier to catch it and replace the leaking part before it fails.
Ours never failed, but a friend of ours had the fitting blow off when trying to extend the slide. The front cylinder kept going but the rear one stopped. Eventually the slide got stuck. We had to disconnect both cylinders to get the slide straight enough to retract it by hand. They had to order and install a new hose and fitting before they could continue on the Alaska caravan.
2013 Adventurer 32H