If it's like the RST I used to have, the two plastic caps unscrew from the fork crown with either a) the special RST tool or b) a large pair of locking pliers. The springs should then come out. Unless you have an extremely long 5mm allen key, you won't be able to get the lower legs separated from the uppers, though.
Also, I had the issue with the adjusters, it turned out they'd bottomed out and when I tried to turn them further, I'd caused them to cross-thread. I managed to get them working again once I saw what the issue was.
TBH, it's probably easier to upgrade. I got a much nicer fork on eBay quite cheaply.