Suspension fork - Can you leave them locked for a long time? My bike's two years old (about 1800km on it, almost all road and bridleway) and kept in a garage. Back in November or so I locked the front suspension fork for road-riding, and over the winter probably did about 50 miles in short ~7 mile jaunts. A couple of weeks ago I tried to unlock my forks, and while the lockout lever moves ok, the forks appear to remain locked; they absolutely refuse to budge even a mm.

I've not had my forks serviced to date. The dealer is saying its because I had the forks locked for several months and neglected to have them serviced. It has always worked quite well.

I think the fork is a "Merida M-510, 100 mm, LO" (This looks like it) - although google finds nothing on that, so I guess its a rebranded something.

So my question - what's likely happened to the forks? Is it something I can fix (and how?)? Is it likely to be a manufacturing defect? And of course, does locking for a long time (even if unused for most of that time) cause issues?

Note: I've read the questions on here about fork maintenance; none of them mention locking for prolonged periods.

Thanks!
Without knowing more details about the fork (coil spring vs air spring) it is hard to recommend anything other than getting it serviced at your LBS.

With that said I know on my MTB with fox float forks, that if I leave it upside down for a while it won't lockout properly. Usually because the oil has displaced within the chamber.

Maybe try flipping it upside down overnight and then seeing if that helps.