Teecee

Hi guys update. So replaced Glow plugs to no avail, then checked all grounds and also wiring to the starter. We found that the connector and a few wires were corroded so got them repaired.
The issue improved so knew we were on the right track, double checked wiring and all was ok. Decided to remove the actual starter and the gear was worn! Replaced the starter today, finally fixing the issue!!
I'm surprised the gear was worn to be honest, I didn't think that was an issue with it being a modern car. It's a pre engaged unit so shouldn't be wearing? I don't know.
Thanks for your help anyways! Appreciate it 🙂