Odd starting problem.

[Gaz85]

i had the same sort of problem sometimes the glowplug light wouldn't come on but once started it was fine after that. but i ended up changing the glowplug relay because we thought it was that then the battery which in fareness it did need anyway but in the end it turned out to be a knackered solenoid on the starter so changed the starter and she fire's first time everytime now.

so i would say try starter. as for the rtx starter's that's what i have on mine now and seems to be pretty good so far mate.