When feeders have trouble puling the tape it's usually a sign that new belts are needed, but I just discovered another potential cause - several of the bottom pulleys that hold the belt down onto the tape had become quite stiff on their shafts, so more force was needed to turn them.
I think maybe dust gets into the bearing - looks like the wheel turns on a brass bush but hard to take apart as the bush just spins - flushing with non-oily solvent and spinning the pulleys seems to ease them off.