97 Sebring convertible seat belts lock up

[seb dad]

Occasionally my front seat belts lock up and won't pull out. It is always BOTH front seat belts at the same time-never the rear. If you are wearing the belts, they will lock in place. If it happens when the car is off, you will not be able to pull them out to put them on. It happens once or twice a month and after a varying period of time, they eventually start working again. I want to give this car to my daughter but won't until this is resolved. The Dealer suggested several hundred dollars worth of tests.
Any ideas?