Intermittent Warm Starting Problem

Seems a common fault with the TD4, nothing showing up on code reader, starts fine on glow plugs where it's cold starting, runs like good when started, even when there is an issue warm starting it always starts after three half turns then one full turn of the key., sometimes when its warm its a lazy turn over! Mystery to me any suggestions! Took it to the garage and it started perfectly everytime ! Its a 55 plate!
I'm trying to rule things out to isolate the problem, possibilities on the table include injectors, sensors, starter motor, fuel pumps etc. Any guidance or advice much appreciated

It could be the starter motor if it's slow to turn over when hot, or does it turn over fast and not fire?

Thanks Kev, I think I have identified the problem. It was a leaky fuel pump, causing low pressure in the system