1970 C10 Door and Vent Window Rubber and Felt Replacement

[GMCPaul]

Some PB Blaster might free up the lock mechanism. If you'll be installing new door seals you might want to check your latching mechanism on the door latch that engages the striker plate. Quite often it's worn and has 1/4" of play or more in it. This then mean the door has to be pushed a 1/4" or more further in to get it to fully latch which with old seals is no problem but with new seals you'll find the extra effort needed to compress the new seals is far harder resulting in a difficult to close door. Be sure to use weatherstrip lube also as it helps.
Paul Sr @ GMCPauls