Mercedes Atego 07 Starter problem

sleepyfolk:
my brother in laws horsebox is on a Mercedes atego, it was fine until he brought it down to cornwall, I guess the salt air has got at the starter motor, now when you try and start it the solenoid clunks and the starter fails to engage.

No, a 10 year old vehicle that has spent most of its time stood unused is what has caused the issues. This is why buying low mileage older vehicles is never a good thing. Jobs like that are best done from underneath using a pit or a ramp.