Outback transmission problem

I checked with a scanner, and there were no trouble codes stored.

I researched the Internet for similar problems and discovered some reports indicating that this might be a common problem with 99-00
Outbacks, Foresters, etc. They point out a problem with an internal
seal of a clutch that is allowing a fluid bleed-down.

Here is one typical comment:

"the fault with your hesitation from park to drive is from a worn piston seal on the fwd clutch pack. The time lag test should be no more that 1.5 seconds from park to drive/reverse. If you apply the throttle you are producing greater line pressure to overcome the lack of pressure in that clutch pack. Then when it does apply the clutch pack with throotle you will get a shift shock. Rebuild if you know your dealer tech is confident in trans rebuiling or just get the reman unit."

If this is indeed the root cause, do you know if it is possible
to change this seal without removing the transmission from the vehicle?

I've always been scrupulous in performing the recommended
maintenance procedures on the transmission, so I'm surprised
to learn that any seal would be worn. Is it possible that
my problem is not due to a worn seal, but instead due to an intermittent failure of the solenoid that activates the valve
which feeds fluid to the clutch?

I recall sitting at a traffic light one day, and I could feel one
slight shake of the car, as if it was disengaging and going into
Neutral by itself. When I pressed the gas, the car would not move.

How can this be caused by a bleed-down through a bad seal if there
is always be pressure on the line supplying fluid to that clutch
piston (assuming the appropriate solenoid remains energized)?

Is there a quick and easy test that can be done to determine
whether it's really an intermittent electrical problem that might
be fixable without a transmission removal and overhaul?

Thanks very much for your advice!