Have you had a problem starting the Volvo 2030 series of engines, the try maintaining the relays on the side of the engine to the rear of the alternator, it has a fuse box on the front end and a cover over 2 relays.
The relays are fine as they are usually gold plated terminals, but the harness is zinc plated so the contact between the 2 deteriorates over time.
So pull out both relays a few times and put WD40 spray on them and the harness.
Hope this helps.
Odysseus
Always a good idea to clean contacts, but WD-40 is not ideal for this. Contact spray is meant for this task.
The reason I say WD40 is that contact cleaner is based on solvent so though excellent cleaner does nothing to keep the contacts oxidization free, where as WD40 leaves behind a residue that permeates the zink plating so avoids immediate re oxidisation.
However, nothing wrong with contact cleaner.
Odysseus