SO Bob you saying that you cannot drain the whole system.. The tank looks like it would hold about a QT. and the filter maybe a half QT. There are 10 QTs in the whole system.. and no drain ?? Any thoughts ??The 1556 does not get the fluid from the rearend that uses 90 weight. The trans fluid is held in a little tank under the seat the cap is on the left side of the seat. As for draining there is no drain on it you would need to take the tank off to drain it and remove the filter. As for the shutter if the tank is full and the fluid is clean I would change the filter and see if that helps if not the pump may be going out and need some work.