I currently have a 1991 SSE- but I haven't had this problem yet on this one
- but I did on my '89. The SSE seems prone to lock failure- not as badly as the SE or LE'* . If the door stops working- lubricating the existing latch is only a band-aid solution, it will seize again. The only option is to replace the entire latch- easy to do. They can be easily obtained from any wrecking yard- the same latch can also be found on the Buick Le Sabre, Park Avenue, Olds 88, 98 and ofcourse the LE and SE models. Before you install the new latch- coat each spring with bearing grease and all moving parts in the assembly. I guarantee after doing this you will never have door problems again. But don't use the latch off of any model older than 89. THe 88 and 87 latches are different (learned this the hard way
My '89 SSE didn't have any door problems for 4 years when everything finally went @483,000km.
So I got a 91' which is still under construction. Many MODS already. E-mail me for any info- I have helped many others.