injection pump o rings diesel
 

my 1992 2.5 5 cyl turbo has a small leak on top of the injection pump.. I have the o-rings needed from my mechanic on the previous repair on my 1990..he only needed 5 but ordered 10 just to be sure and gave me the 5 50¢ rings he didnt use.. the reapir cost me 123.95 as i recall.. I also have the correct socket spline fitting to take out the pressure valves.. my question is since I have never done this repair is it simply losening the fuel line 13 mm nut that leads to the injectors and just refitting the oring in the pressure delivery valve? is this a simple D.I.Y. job or should i let the pros deal with it?
the leak is ever so small but it looks like a simple repair.. if anyone has attempted this and can give me some advice i surely
would appreciate it! i would love to do it myself if its not to hard and save the hundred or so bux!
thanks in advance!

car has 140k on it and pump has never been fooled with