63 wiper motor release cam interchangeability?

HELP! My wipers don't work. Switch is good, motor turns linkage, only if you put pressure on it. I'm looking for part# 2421 845 for my 63 GT convertible. Can the wiper motor cam and release be interchanged with any other year? I know that this is one year only. If the wiper moves by putting pressure on the linkage arm. Does this indicate that that the motor arm bushings are bad? Can the felt itself be replaced or do I need to buy a kit for this? Collectors Auto Supply website says part is $34. Is this the only source for this item?