I've blown the 30A fuse on both the power tongue jack and the slide out.....not sure why. I carry a couple of 30A fuses (Green) in case it happens again. It hasn't happened latley.
Probably best to buy a resettable fuse as mentioned and you won't have to worry about crawling under the trailer to replace a fuse.
2009 GMC K1500 4x4 Crew Cab
2012 Roo 23SS
E2 Trunnion WDH (1,000 lb / 10,000 lb)