Automatic door locks

2000 GMC Safari Van 120,000 miles

For the last few months nither the remote or the inside buttons open the locks. All four locks click but it's like they don't have the power to unlock fully. They seem to move about half way but not entirely to release lock. It's the same for all four locks.
I can open with a key or slide the lock open inside.

Thanks for any help.

Gene