Its annoying enough dealing with three different coupler styles on the layout already.
What style does the chuggington series use?

Hello,
I have a 6-8 year old HO "plus series" gp35. The electrical contact is a sort of leaf spring from wheel to chassis and they've become flakey. Loco speeds up/slows/stops depending on the curve of the track as the trucks turn..
I've tried cleaning/sanding and bending the springs and only made it worse. Now i go the the web site looking for parts and a see new trucks that appear to have direct wire linkages from truck to chassis. 
Thinking of hard wiring mine - anybody tried it? I  guess i need to still rely on the spring to wheel contact and somehow connect a wire to the spring as the truck frame is mostly plastic.
If that doesn't go, can I upgrade to the new trucks? $10/per isn't bad but I don't obviously want to find they simply don't fit..

G