After reading this forum, I got the nerve to attempt a removal of the left rear door panel on my 97 XLT to access the lock mechanism. The door could not be opened from inside or outside without removal of the panel. The culprit was a broken spring, interior to the handle return mechanism. If the spring breaks, the latch activator rod (threaded and with a plastic part on its end) will be stuck in the full down position. As such, the latch will not be engaged unless the rod is pushed upwards, towards the broken spring.
The fix is simple. I went to Home Depot and bought a Handyman Spring, SP-9602 (Prime-Line Slide-Co), $1.95 for two springs. I hung the Handyman spring onto the broken Ford spring, which had slipped down over the latch handle interior mechanism, making a good anchor position. Next, I took a 6 inch section of metal coat hanger and put a a loop the end using a standard shop screwdriver as a template for the hole diameter. Now I bent a right angle into the loop end so the part then resembled an "L". Put a loop in the other end of the hanger to attach to the Handyman spring, after fiddled a bit with the correct length to just get a slight positive load on the spring and the job was done. Since the springs come in sets of two, I made a precautionary repair of the still-functioning right rear door.
The driver side door had a broken handle-return-spring as well (where is Ford purchasing these sub-standard spring??!), so back to HD for another set. This broken spring issue can render the rear seats unsafe in a crash, since the doors cannot be opened for an egress.
Each door can be repaired in about 20 minutes using this method, and functionally, the new spring does the job required. Write to me if you want some detailed pictures.
