Reactivating this thread because I've just rewired my starter solenoid so it fires direct from the battery via a relay. My starter is the geared variety marked Magneton & "failed" after 2 hours! Thinking it'd been over-cooked at the Ring I was all for buying the "race version" which is supposedly bullet proof.
So why should this cure the problem? The starter solenoid is activated by the ignition switch via I suppose another relay (MFU: what's this?) so the current should be adequate to "throw" the solenoid. And why should heat affect this so far away from the engine? I have a Vecta imobiliser which isolates, amongst other things, the starter circuit. I'm wondering whether the Vecta is the cause of the problem. With age & vibration (& maybe a little heat) it may be offering too high a resistance to "throw" the solenoid but enough current to activate a relay.
Of course this won't cure all starter problems, especially where soldiered joints have failed, but it seems to cure this one. Fingers crossed!
Mick