Well I,ve just bought a second hand Panzer 3 non S+S, that too had two speeds but high speed was intermitent, if you open up the transmitter and look at the contact for the speed stick you will see it has two small fixed contacts for the forward slow and fast speed, in my case the fast contact was not being touched by the other half of the switch even though the stick was pushed fully forward, as the 'trim' levers are glued I just gently bent the moving contact so it touches the fast segment at full stick travel. It really is easy to sort out, cleaned the contacts and it now runs fine, I have recently bought two non S+S (panzer 3 and Tiger) for very little money, whilst they are not as good as the later Tanks they are good value and can be upgraded as and when required.