I have a 643 model Bobcat, 1988 model year. Tilt cylinder was replaced last month as cylinder and piston end was deeply scored and seals destroyed..Now it is again failing to hold in position. Probably has more loose metal in fluid causing seal damage. I want to repair it myself, that is if cylinder is not scored as last time..I have quit using it hopefully to prevent deep scoring should metal flakes again be the problem.. I watch the mechanic take the cylinder loose, but did not witness his taking it apart..where do I start? Bobcat want an arm and leg for a new cylinder, this rebuilt one was just an arm.. Metal in fluid? Does not the filter clean up some of this? Change filter again etc??? Any suggerstions would be appreciated..