Checking the timing is quite straight forward, (for me) but I don't know how skilled you are
Above the starter motor is the flywheel sensor that needs to be unplugged and removed using a 10mm socket. It's just the one bolt holding it in
Watch out if there's any washers
Insert the 13mm dowel(drill bit) in, (you will feel and hear it stop against the flywheel) Now using (probably an 18mm socket/wrench) turn the engine over slowly, until the dowel/drill bit goes through the flywheel and positively locks the engine
It is important that you don't use a 12mm or any other approximate size drill bit, as the accuracy of this is critical
Now remove the rubber bung (if it still has it) from the plastic cover ahead of the injection pump
Now see if the (6 or 9mm (not sure at 2am)) drill bit fits right through the pump pulley
If it does, then the timing is fine
If it doesn't, you've found the problem
You may be able to look and see the alignment with a small mirror and torch
Don't forget to remove all pins before attempting to start/turn over the engine