Probably the printed curcuit thats making poor contact with the bulb holder--common dilema on these trucks...
I can get my bony hands up in there to remove the bulb holders ,after contorting my body into a pretzel,its not easy,but can be done without yanking the cluster out..I also found I was able to reach them by pulling the glove box out and down out of the way too--but my arms are long,and it would have been easier if they were 6" longer still!.. I had to yank the "brake" light out of my 82 K2500,to get a sticker,the dam thing wont shut off!.