Thanks very much for the advice on this. I will do the check as suggested.

If you checked the fluid without the engine running and parked overnight, that level is normal. All of the fluid will have settled into the sump.

The correct way to check the ATF fluid level is with the engine running.

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Keeping it running is better than buying new

Your call. Too much fluid might harm the tranny seals. Are you familiar with the transmission? On the bottom there is a drain plug. It has been a long time so I forget the size wrench you will need.. Anyway, loosen the plug enough to slowly let out some fluid. Then measure that amount. One method would be to let out a quart as a starting point.

Then drive the car for at least 15 minutes to warm the tranny. To check the fluid level warm, idle the car on a level surface, then row back and forth slowly through the gears for a minute or so. Then with the car still idling, pull the dipstick, wipe, reinsert and check level. That should give you an accurate reading. If it is too low, you can always add some more ATF. Better that than too high as you'll have to repeat the whole draining process...:)