[crd14]

Check both mecanical and vacuum advance. Use a timing light and check base timing then disconnect the vacuum advance and rev the engine. Timing should advance. Reconnect the vacuum advance. If timing advances as soon as you connect the hose then it is connected to a manifold source and it's working fine. If you connect the hose and the timing doesn't change then rev the engine again and if the timing advances more quickly then it did with the hose disconnected then, again, it's working fine and your problem lies elsewhere. If you don't get these results repair as required.