Hi guys! I have a problem with a Linde H20D truck. Serial number 351909046320/1989. It is a single pedal model. When pushing the gas pedal the truck moves but quite slowly and does not seem to be able to pick up speed. After rolling for say 10-15 meters, it picks up some speed, but it lacks the kick it should normally have. I have just learned that we have a problem with the rockers push rods rubber covers - they are gone/melted. I have also realised that the engine gets hot very quickly, in a mater of 50 meters and there is a slight smell of burn rubber. Any ideas?