Once in a while, beyond deep cleaning, even taking the machine apart may be needed. I tackled my own punchcard machine recently, here are photos of the action in progress
Needles now back in, needle retainer bar restoration left to go. In case you choose to tackle the process on your own, some clear instructions may be found at Knittsings for Brother machines , and on Susan Guagliumi’s blog for Studio brand
For folks that prefer videos Roberta Rose Kelly has a series of maintenance related ones on youtube.