'99 Sierra power door lock issues

[chrisinestes]

My '99 Sierra's power door locks are showing their age. The key lock turns so hard that I'm affraid the key will break. The automatic unlock function, when it's put into Park, or I use the key fob remote, unlocks it just barley far enough to be able to open the door. It's become S.O.P. for me to slide the manual lock slider to "open" so I can get back in, but one of these days, I'll forget, and the solenoid won't unlock it, and it'll cost me a bunch of money for an unlock service call.

What part(s) are the likely culprit(s)?

Thanks!
Chris