The first thing to try might be to leave the deck on overnight to see if some capacitors need to reform. Old caps can get leaky and pull the operating voltages down. The capstan might need lubrication. Try giving it a twist with the tension arms armed. If it starts to spin up it probably just needs some lube. Or you may need to get inside the deck to see if the capstan motor controller is on a plug in card that might need reseating. Supply motor could be a brake adjustment issue. Or, if it's slow when pulling tape, your tape might be sticky.