Odd Starting Issue

A buddy of mine has a strange issue,

He took it to the independant landy garage for a 24 month service, we normally to the small service but like to get it checked over by a garage every once in while

The problem he is having is that his landy is now having to turn over a couple of times before it starts most mornings.

The garage had now replaced 3 out of 4 glow plugs and the fuel lift pump after having it for a further week but the problem has is there?

any ideas?

I have checked the leak of tubes but nothing obvious

its a Defnder 97' 300tdi 90

Many Thanks

have a look at the fuel filter, if its half full, id expect leaky injector washers, ive that problem at the moment, if not id swap all glow plugs for new LR parts, but from what i hear u hardly need glugs at all on a these engines??