Just did mod on 40+ year old Dover job. Balanced car, releveled platform, added new isolation, added new steady plates, tensioned cables and all roller guides are perfect. Ride qaulity is near perfect on platform, cartop and cross head according to PMT aside from the fact that you cannot physically feel anything. The shake is only present in cab walls and unfotuneltly the property managers method of testing ride quality is resting on the back wall handrail. Only thing I can come up with at this point is the fact that I removed 2 cab interiors that were built on top of each other and installed a very lightweight "snap cab" to the cab shell which the is original 3/4" plywood. Think I may have lost some rigidity when removeing the other an shells. Open to any and all suggestions. Thanks.