If the fluid level is normal, the clutches are probably shot. A professional rebuild will run approx $1500, a little less if you remove and reinstall the transmission yourself. There are no bands in this transmission, and therefore no adjustments to be made.

Or you can attempt DIY rebuild. The master rebuild kit runs about $130, and includes all the parts you need. I have not attempted a rebuild myself but others on the board have done so with success.

Or you can get a used unit from a salvage yard (which is what I recently did for a 740). I bought an clean and drip-free AW70L from a '92 940 for $250, and I have been very pleased with it so far.