Fiat Tipo 66 plate... Car has been intermittent with starting. For example, started it this morning at 6.30am to move out of the way of partners car, then went to start at 8am and it wouldn't start, just clicks. Tried jump leads to no avail but bump starting works everytime.
Want to know if I should be replacing the battery or if that's unlikely to be the problem?
It sounds to me as though the solenoid for the starter has gone bad. At the back of the solenoid, there is a large copper washer which comes in contact with the main power lead contact and transfers power to the starter. If this washer becomes corrupt, it will intermittently transmit power and allow the starter to spin sometimes. You may be able to change out the solenoid itself, but in most cases it is only sold with the starter, so you'll end up changing the whole thing. You should be able to take the starter to a parts store to have it tested.
The cheap shot is to check every connection on the "fat cables" -- both the live, and the earth to the bodywork (this might go to the engine and have an additional braided earth strap from engine to bodywork). Every connection can corrode, but the ones closest to the ground are most likely, and the filthiest and hardest to reach.
You can check for a voltage drop across each connection, with a helper to turn the key. Or just separate, clean, grease and refit every connection point.
I once had a car where the earth braid was broken, and the only earth return was via the metal outer sheath of the throttle cable. I only found that one because the cable welded itself to the outer sheath.
