I am working on a elderly neighbor's LX188. Tractor is in excellent shape, Kawi twin runs fantastic.It came to me because it would jerk and moved very slowly. I found out it had been low on Hydro fluid and refilled. Knowing how fussy the hydro units are I was advised by JD dealer to change out the fluid as it "often makes a big difference". Tuff Torq recommends 5w50 synthetic for that unit so I ordered some and drained/refilled per Tuff Torq directions.
Now the tractor operates fine on level ground but will not climb even a slight grade and barely climbs a small ramp into the shed. This is not an engine issue. The drive belt was replaced by one of her sons last year. Could belt tension be an issue?