87 300e Turbo Hard Starting

[SoCal Diesel]

I am getting an 87 300e Wagon Turbo Diesel tomorrow. My friend is the original owner and has owned a few diesel Mercedes over the years. He said the car was gradually getting harder to start until one day it wouldn't. He thought it might be the glow plugs. He towed it to the shop and since it has been there 5 months since the breakdown, the shop foreman cannot remember what exactly is wrong and the work order cannot be found. He vaguely remembers the problem as possibly injection pump timing because he said it DID run but was very hard to start. That is all I have to go on. I would love a few suggestions of what to check upon initial inspection when I get it to my house tomorrow. The car has 234k and has had timely services during its life. A member on BenzWorld suggested delivery valve seals on the pump, but could timing chain stretch also cause the pump to be WAY out of time it will not start?