Fading door locks on 99 Suburban

I have a 99 Suburban , whose door actuators fade after their first activation (open or close) and then get weaker and weaker until they barely move after pressing the door lock/unlock button or using the remote. The truck has a Clifford G4 alarm.The wiring does not tie into the OEM double relay under the steering wheel.when the relay cover is removed the relays switch cleanly in the lock/unlock activation. Any ideas ?                          Steve Sierz

Hm. No idea why removing the relay cover would make them work better. But GM doorlocks get sticky and slow all the time. Look carefully......do all the doors behave the same? If one day all of them are perfect, and the next day they all work like crap, suspect the relays. But if some of the doors seem to work better than others, it's time to pull panels off and start lubricating stuff.