I just went to the Glendinning website, and they have an owners manual that gave me some potentially valuable information.
We have that system on our '06 Dynasty. When the coach was new (2nd outing following manufacture), we had the same problem you are experiencing. In our case, I think the brand new cable was a little sticky, or tacky, due to the new and somewhat soft rubber jacket. It would only come part way out, and would only go part way back in. We had to coil it in the bay to travel, the next day. I might add, it was quite cold (Ely, NV in early January of 2006). We fought it for two days, before it would finally move further. Fortunately, it finally did. One takeaway that I had was to not overly clean the cable as it retracts. Even at 13 years of age, the cable can still have a pretty high coefficient of friction and potentially hang up. I wipe it with a dry rag as it goes in, but I don't try to overly clean it.
One big takeaway from the owners manual I downloaded is the fact that there is a manual override on the unit. Try the link below and see if it will download for you. It describes how to use the manual override. Hopefully it will let you get the cable out, and once out, you can clean it up, but be sure not to clean it to the point of tackiness or stickiness.
I was thankful we had a 30', 30 amp cord with us, along with a 50 amp female to 30 amp male adapter, so we at least had power in Ely, that night!
Good luck with solving your problem.
Also, our cable often will stop extending or stop going in, but a momentary reversal of the control switch along with physical help in the desired direction of travel has always gotten the job done. Knock on wood, right?