After buying a Q1 (Hornby one) I was eager to try it out. Unfortunatly the wheel rim width is slightly wide and causes a short circuit on some points. A possible solution is to extent the 'frog' by painting (in black or rusty colour oil paint) on the corner where short circuit occurs. Tip for viewing the track on the other side of the engine I have found that a macup mirror from christmas cracker helps this way you don't need to lean over too much.

On the downside painting obviously increases the length of non-contact and this may not be liked by some of the older engines which have less pickups. Also it has to be refreshed at occasions when the paint rubs off.