I would love to know how much impact the bearing has on sound quality
A lot. The same said once you have it in its normal position. If you are gobsmacked now, wait until you get the bearing sorted.
I will be home in about a week and I swear I have some photo's of the deck with the new 'motor arrangement' if you need any help. Presuming you have the same problem I did of course. I will be happy to help.
You sound a bit like me here. Once I heard the PT I up and running I was on a different planet with the sonics. I waited 25 years to own one and well worth the wait.
I'm from the old school and still believe a change in the deck brings out a different aspect from a cheaper cartridge. It makes it live. I would like to think it's the PT1 over the LPT.