348 Starting issue (starter motor fine)

I've had issues starting my '89 348ts for a while now (really, ever since I bought it). Sometimes, the solenoid would click, but not turn over unless you tapped on it. I read some threads on troubleshooting this, and actually pulled the starter a while back and smoothed out the plunger ring and contacts. This helped for a while, but the problem just came back. This time, I bought a re-build kit with brand new plunger/contacts and pulled it again. After re-building, I put it back in, but now there isn't even a click when I turn the key. I bench-tested the starter and it worked fine, then put it back in the car and manually jumped it (screwdriver from the battery post to the ignition contact) and it started right away. I was reading that sometimes there is a wiring twist connector near the top of the left shock absorber that can come loose, but am not sure exactly what this connector looks like. Can anyone describe this better to me/have a pic? Also, how exactly do I test voltage from the ignition lead with a multimeter? I have read I should do this, and while I'm ok with fixing mechanical issues, I'm less familiar with electrical problems. Side note here: when I turn the key, the lights dim slightly, so I think it is at least drawing from the battery at that point. Any advice is greatly appreciated!

 

I will check into that today. About testing the ignition lead, would I put the (+) lead of a multimeter on the ignition wire and the (-) lead to the (-) battery post, then turn the key? I have heard that if the voltage coming from that wire when you try to crank the starter is much below 12v, it won't turn over (I also want to make sure it is not 0v, as this would indicate other problems). I have also read that there is a ignition relay that can be installed if the voltage is low. Thanks!

 

I ended up finding out there was a .7v drop through the ignition switch, so I installed the Bosh relay and it works perfectly! Can't complain about a $25 fix!!