Slipping manual tuner selector

Question

I have an excellent Goodmans 120 tuner amplifier with superb sound quality but I cannot select broadcasting stations . The chord attached to pointer dial can search/sweep in one direction but I cannot get the dial to return the pointer in opposite direction without assisting the flywheel by hand .The cord appears to slip.. I would be most grateful if somebody could give me some help in rectifying the problem . my email is len.dacruz @ gmail.com