I'm glad you started this thread. I've been wanting to build something better than my Jethro2 and this thread kick started my brain. Already found a 5A mini vac at Goodwill and the motor looks pretty much like yours.
I've wondered about those motors but never gave it much thought until this thread. Hmm, now I just have to scroung the shop for the rest of the parts.
If you can sit them together and it still reads different I would replace. I try to use identical tc's if I can.
If one has a different case / probe to the other then you may get a difference based on the inertia. You could try swapping and see if the problem follows the tc or the channel?
btw, my fc is between 213 and 215 on the ir when the tc reads all over the place, sometimes it is 20c off. I found it sensitive to placement. When the beans are floating you are really reading the air temp around. I found increasing the air speed showed a different temp.