Volvo: Overdrive slipping, transmission failure, transmission flush

Question
My 1994 850 (non-turbo) has been diagnosed with a code 3-2-3 - the converter lock-up occasionally fails to engage. One one particular cold day this week, I could really feel the slippage when I first took off down the road.  My mechanic reports the transmission fluid is dirty and advises a transmission flush, which I'll have done this week. He thinks that will take care of the problem, but I'm skittish.  Can this type of problem be symptomatic of a bigger issue - pending transmission failure? Of note, the previous owner of this car had the transmission rebuild less than 30,000 miles ago.  Thanks in advance for your help.  

Answer
Joe,
I would go ahead and flush the trans, at this point it could not hurt. If you continue to have have the problem you may consider getting to a shop and have them advise on the next course of action. Are there other codes that are also in the trans like 313 gear position sensor? There have been may problems with that sensor. It might be worth replacing.