42RH advice needed

I managed to get the car in the workshop for a few minutes today. It looks as though the kickdown operating arm is very slightly longer than I need for this application. With the throttle closed the kickdown lever is about 1/8" back from fully forward and at WOT the lever could still travel another 1/4". Would that be enough to cause the slip?

I drained a bit of fluid from the transmission and it looks a good red colour. I can't smell any cooking smells.