Volvo Repair: 1996 Volvo 850 transmission, volvo 850, diagnostic fee

Question
The tranny shift arrow started blinking this past friday so I parked the car and saturday i took it to the dealer. They pulled the code and I dont have the paper with me but it was an internal code reguarding the torque convertor not locking up in gears 2-4.  I asked about replacing the solenoid and I was promptly told they do not do that. They want to charge me 4000 to install a reman tranny.  I paid the diagnostic fee and left.  Its a 1996 volvo 850 2,4L NA with the aw50-42le tranny. I know this is a toyota tranny and I could probably get parts for it at a toyota dealer even though the volvo part dept had the solenoid.  Think it would work alright if I flush the system, R&R the solenoid, install an inline filter, intall fluid, clear the code and let it ride?

Answer
the problem with the dealer just doing the parts like this is they ahve to stand behind it for a year.usually there are other problems in the trans also so after doing this there is sometimes other failures.the easiest thing for the dealer to do is in stall a reman unit.what you suggest would be worth a try.