Before you replace a part or the whole thing, first try taking the window off the door and see if it works then.
Those window tops have a tendency to bind when installed if one of the bolts is tighter than the other.
If it works off the door, then reinstall it with the bolts loose.
As you cinch them down alternately, repeatedly try the lock to make sure it's still working.
Arthur M Vigil
Former owner of:
'95 RRC - 3.9V8 Rimmer Supercharged!
'72 Series III 88" NADA Turner 2.25 petrol (Lovely Rita)
'95 RRC Brooklands/TWR Edition 3.9V8
'97 D90SW NAS #2426 - 3.9V8 Rimmer Supercharged!
'95 D90ST NAS#2620 - Original owner