30 miles isn't too bad...just that it should have worked.
Anyway, make sure after it gets "repaired", run that slide in/out many times, maybe 10+, and after each full movement, check that it seals tight and there are no gaps. In other words, make sure it has been adjusted and aligned correctly. With it not working right now, misalignment is a distinct possibility.
I had to deal with an alignment issue on my slide and it took multiple attempts for the RV place to finally get it right...and I had an 80 mile drive each way. The alignment issue would cause one side to jump a tooth or two on the track and then created a gap in the back when fully closed. The last time I went to check on my TT's slide, I moved it in/out about 7 times and it jumped the track again. Dealer felt bad and promised to get it fixed correctly...seems like they may have been cutting corners with only minor adjustment. He said it would be fixed and they delivered it to my house 80 miles away and extended the warranty.
I've not had a problem with it since.
I love me some land yachting