Faulty Rowing machine (Broomgrove TN34)

Roger Black rowing machine. Bought from eBay but it never worked properly-very stiff, even on lowest setting and I can’t get the timer to work, although some of the controls do work. We tried to fix it, took it apart and loosened the belt but with no joy. It may be fixable if you’re better at that kind of thing than me?! Anybody want a challenge before it goes to the tip??