Likely they are just worn and the actuator no longer has the muster to move them up, however they may still lock ok. If it were a relay issue that would likley constitute a non power situation. but based upon the information you've given, Id say that you and any otehr previous owners got you $$$ since 2000..
check on rockauto.com for replacement units OR, you could stop by any audio shop that carries alarms and just re[place them with aftermarket alarm actuators, I think DEI has them listed as T-524 (?) Its been awhile. They will offer two kinds everywhere you go. Dont buy the blk ones, get the blue ones they're better made and will last you longer too.
https://www.newegg.com/Product/Produ...g&gclsrc=aw.ds should you go the alarm route.
Neither is better than the other one, but at a slightly higher cost, the originals will be less work adjusting for movement.