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It sounds like you may have an issue with a dealer not up to current technical troubleshooting.
There is an ECM motor tester that we use on variable speed motors and it tells you right away what the issue is. It appears they are changing parts hoping to find the cause.
It is possible the motor was affected...but then the furnace would still fire up, create heat, but the blower would not kick on. Are there any codes? What is current operation?
This is one of those that I wish I could be onsite.
With power on...does the circuit board light illuminate? And if so is it solid or blinking?
Also here is a manual with troubleshooting to help work our way through
Keeprite Variable Speed Furnace