windows really tight

Any ideas how to loosen up the manual windows on my 93 2600i?
They are really hard to roll up or down.

Mine are very tight too .. haven't had a chance to check it out yet, but i assume I'll have to take the door panels off and adjust the linkage - could be bent.  But then again, I don't know the inner workings of the door yet.  :)

OK, this is from my VW bug: I've had to take off the door panels before and clean the big gears, like with brake cleaner or WD-40, then use stick lubricant (from Ace Hardware) to lube those gears, then put panel back on.