Thanks to all of you for advice, have used Isopropyl neat solution and taken all the rubber off down to the black shiny plastic because when partly cleaned and rubber dried, still sticky. conclusion after 10 years of use, the large rubber areas where your hands go have de-composed. The controls have always been as new but the rubber coating failed. I used a "rough" cotton pile tea cloth when the wife was not watching, rubbed carefully but vigorously to remove all rubber down to the black shiny plastic, taking care not to apply the liquid to any other areas, when dried, a small amount on a soft cloth with kitchen spray polish and the controls look brand new. To attempt to dismantle the controls is unadvisable, so clean all the Throttle area of rubber only and clean the Stick rubber area where your hand sits only. Very pleased with the result.