This is weird. Won't start... Sometimes w123 1982

[scoodidabop]

I have a 1982 300td. Here's the problem: I went to fire her up the other day after my lunch break the other day, and nothin!! Crap! Seems like the starter, right? So I dropped a new starter in right there in the mall parking lot. Tons of fun.

Worked just fine. Way stronger starts than before.

Now here's the part I need help with. Sometimes the starting is not reliable. Generally, the longer I let the glow plugs heat, the worse my odds are. So I'll have to turn the key back, then go straight to firing her up. That doesn't always work though. The only other quick fix it seems is to throw the car down into drive, then pack into park. That seems to do the trick, even though yesterday I did that trick 3-4 times before she even wanted to engage.

Just FYI, when the problem is happening, the starter isn't engaging; there's no cranking. Just a simple "click!" before my heart starts sinking.

I love this car! I need to know how to diagnose this starting problem. Seems electrical. My relays are fairly new, I think they're okay. I don't know what else it could be.

PS - This forum is the best thing to happen to us DIYers.