Case 2090 transmission problems - no power shift #1

Started my Case 2090 power shift this morning and it would not move in power shift #1. Sort of feels like it is going to move but doesn't. If you continue up to power shift #2 it will take off. Off the top of my head if the clutch is pushed in and you pull it back into reverse it will not move either. But, with the clutch engaged and if the power shift is pulled into reverse it will go backwards, I think. I didn't spend a lot of time with it as I am planting, but this is the first time the transmission has ever gave any problems. I drove the tractor into the shed after harvest, gutted the cab upholstery and drove it 5 miles to the car wash to clean the inside of the cab - NO PROBLEMS WITH SHIFTING. It has sat there for maybe 4 months without moving. I did change the transmission/hydraulic oil filters this morning after the problem was realized. I think the transmission was a little low due to some drips at the PTO, but did bring it up to mid range on the dipstick and still no solution. When I washed the cab I wouldn't have gotten something underneath too wet and now it is hanging up? I will spend a little more time on it tomorrow. Did the tractor lose a seal on a clutch pack just sitting there? What other problems should I be looking for? Tractor has less than 3000 hours on it. Thank you.