mate it sounds to me like your starter motor is just plain fucked lol

it cant be charging problems if it starts when u leave it overnight. If the battery wasnt charging properly you wouldnt be able to start it at all once its flat.

ive got a mk3 cabby converted to S2 turbo, retaining the original loom, my battery lights glows ever so slightly but mine is all good. I take it u only notice the battery light at pitch balck night, cos its that dim?

Tellin u mate, starter motor, fact of life on CVH's, along with oil leaks, blue smoke, TAPPING.....good engines really NOT!!

do you have a volt meter??