Cut your losses and replace this boiler;it's an antique.
Put a Biasi or similar in.You'll reap the rewards.
Should cost you around a grand depending on where you live.
Joshmcfe, January 2009
Babs,
You need to say what your boiler is doing - you know - doesn't do this when it should or does do this when it shouldn't - else the best you'll get is mere sympathy.