My 85 had the same problem.  Drivers side intermittent & passengers frozen.
 I squirted WD-40 and other assorted chemicals into the lock semi-religiously
for 8 months.  They still never freed up.  Finally on a warm spring day after
a cold Vermont winter of walking around to the only free lock I removed the
offending locks.  They are easy to remove.  I stood them on end, opened the
keyway door and poured 6 in 1 lubricant in.  This flushed out all the crud
and relubricated the lock enough to work ever since.

You might want to do it before winter like I didn't!

John Fleming

85 Westy
79 Camaro 
54 Ford Pickup