1975 starter issues, Starter doesn't disengage Options

[Bryce]

Hello guys new to this forum, but have had multiple 914s,I'm working on a 75 with starter issues. Had a friend bring his 914 to me to work on carburation etc... When he got here I when to start it and nothing so checked wiring and it was fine. Tryed jumping starter it was locked up solid. He live about 3 miles from me and stated that he did here some grinding type noises . He just had a remanufactured replacement starter installed. I told him to get another so he did same thing Bosch reman. I installed it and it's doing the same thing once you turn the key to start it, it doesn't disengage. I've changed new ignition switch new starter relay(aftermarket). I'm at a total loss, and very frustrated doing this as a friend and am over it. Any suggestions? Also I pulled starter bolts out and grounded body to run starter in the open and running or bench testing it the solenoid doesn't push out. I thank it's possessed. One other thing is he had a shop swap his injection for China 40idf carbs. Of witch they don't have any vacuum ports in them or the manifolds, should it be ok to tap into the Manifold for distributor vacuum?

[Bryce]

Sorry the starter being locked up was the first starter. The one I'm dealing with not disengaging is the second starter. I am also thoroughly confused about the whole thing. When I got it. I installed the new starter and new ignition switch, the owner had already installed a aftermarket starter relay, of which after some reading is not the best idea. So after installing these two things when I turned the ignition key to start there was nothing. So I traced the big yellow wire from ignition switch back to starter solenoid and wasn't getting any power to solenoid when switch was activated. So I traced wire and there is a break in the yellow wire somewhere. I tore the interior out of car to get to wire harnes. The yellow wire goes into a box under the passenger seat. So I ran a new wire from the yellow wire back to the ignition terminal on the solenoid . It starts but like I said the starter doesn't disengage, so it just sits there grinding away until you turn ignition off. So here's were it gets weird when the starter is bolted up, the solenoid ingages, but doesn't disengage. If I unbolt the starter and energize it it spins but solenoid doesn't push out.(ingage) what is the black box under the passenger seat? Also most all the plugs under the seats are unplugged or ends ripped off. I'm assuming seatbelt lock,start system?