Anyone had these symptoms with a 904?

Drop the pan and check the filter. Whining sounds like pump cavitation. Restricted filter will do that. I had 71 Demon slant 6 years ago that was given to me with a bad transmission. It would shift through all gears for about 1/8th mile then loose all forward gears. Reverse still worked. I dropped the pan and sludge and gunk were in the pan. Dipstick looked red. The trans would shift fine until the gunk was pulled up against the filter then it would loose line pressure. Clean pan, new filter, new fluid. I drove it over 200 miles the next day.