How much grease did you use on the trany gears, the plastic gears really should not be greased at all.
If it was a very small amount of grease you should be OK, but if you were liberal with the grease then you need to pull the trany out and clean out the grease.
Post up the lid pics! :thumbs-up::)
With the black trany that still has revrse you cannot spin the spur fast enough by hand to make the fwd/revrse pawls swing out and catch the shift drum, you would need an air compressor and a blow nozzle to get going fast enough.
If you decide you don't want the revrse, get a FOC for it for...