Have a 2000 registered Sprinter 308D LWB. Usually starts first time. Yesterday glow plug light initially NOT coming on but lights up after a few seconds and then doesn't go out. Weather quite mild so waited a minute then tried to start. Engine turning over fine (new battery) but won't fire. Is your money on Glow plug problem in which case can someone give me clue as to location of fuse/relay or starter motor? Thanks for any help.