Hi guys. I've got a bit of vibration I'm trying to figure out and would love some insight. Here's the back story...

A few months back I bought a 1990 Si to upgrade from my 1991 DX. It's a Canadian model (ED7 chassis) with an automatic transmission. It was slipping going into second gear, but came with a spare (allegedly good) transmission the seller would be willing to swap in. He works as a technician at a dealership and would do it there on his day off. The job took him a day longer than planned and I ended up having to fine tune the throttle cable myself to correct the shift points. Not exactly surprising for marketplace cash jobs.

Now the swap is complete but I feel a vibration that definitely wasn't there before. I would almost describe it as being felt through the gas pedal. Nothing crazy, but like a heavy buzz you feel in your foot. It definitely intensifies as RPMs increase.

I checked for these symptoms in the transmission troubleshooting section of my service manual. It said vibration after repair might indicate the torque converter isn't properly seated. I've also read that this could indicate the TC is bad.

Does anyone know if the seating of the TC can be checked or possibly even fixed through the service window where it bolts to the drive plate? Ridiculously optimistic, I know. But I feel like if I have to go through the trouble of pulling the trans I'll just put a new TC in.

Which leads to the most important question. Does this sound like a TC problem or should I be looking somewhere else? If there's a way to confirm or rule out the TC please share.

Cheers