2001 Subaru Outback "SCRUBBING" OF WHEELS ON TURN

After changing all tires, I noticed what is best described as "scrubbing" of the wheels on turns in forward or reverse gear(s). More scrubbing on more severe turns. No interference straight ahead; little when coasting in a turn and less when the engine is "cold" and just starting out. It is somewhat intermittent
The local mechanic has diagnosed it as a solenoid in the manual transmission that controls the variable wheel turn while cornering that's failing. They have found clutch debris in the transmission fluid. The suggestion is a new or rebuilt transmission.
Questions: Is this a reasonable diagnosis? Are there other possibilities suggested by the presentation of these symptoms? Couldn't the transmission debris be coincidental to the solenoid problem? Should the transmission be "flushed" of fluid and fluid replaced? Is it necessary to replace an entire manual transmission to replace/repair solenoids? Is there more than one solenoid in an all wheel drive drivetrain? Is a transmission shop the best alternative or a Subaru dealer. Or independent shop?