Katy,

You are dealing with a mazimum lifting height sensor switch on the mast or lifting height potentiometer ( mounted under the driver seat and hooked to a cable that is anchored to the bottom of the mast and it start counting when the operator compartment starts up.). A lot of times the cable gets broken off at the mount by debries, very little pot failure. - check settings in FZS control also.

Please give email address for further information