About the 1.8 amp PTC, is this a standard size for all small loco's that you install? I would guess that for a larger loco ( which probably doesn't need the extra set of roller(s) since it usually has 2 to 4 rollers under the engine), it would require a larger PTC amperage rating. Maybe you have never experienced this with a larger loco. If you have, what would be the size of the PTC value in this case. Could you supply the part number of one or both PTC's and the latter PTC's amperage rating. My guess is you got the PTC from Digikey. Thanks for sharing the experiance, it's great info!!!