Update:
I tried the 3600kv speed 400 6v.
Not a good option, unless one would like to go to an 11-tooth pinion (an educated guess). With a 16-tooth, a speed400/6v has a good top-end, but accellerates sluggish and battery and motor run very hot.
With a 400/6v on 7,2v and an 11-tooth, You'll prolly' get some nice extra accelleration, but loose out on the top-end.
I machined-out the idler gear to fit tiny ball-bearings that I had lying around. No idea what size.
It fit the axle with the help of one of those copper eye-lets that come with servo's. It helped some in the noise -and wear -department.
I also ceramic-greased the axles of the bogey-wheels and idlers. That helped tremendously in the squeeck-department. The track runs pretty smooth, and doesn't "flap" around so much.
QUESTION:TechyJoe, how did You get the idler-wheels off to open-up the track "box" ? I tried brute force and some leverage, but it only succeeded to crack the track-"box" for a bit. Cyano-Acryilic to the rescue
I figured that, with some luck, there are flanged-bearings that will fit the bogey axles. I am somewhat sceptic about the wear-resistance of those holes in the plastic.
Plus I want to install two oil dampers like You have. Under heavy load, the track hasn't got a whole lot of throw left, and slams in top of the tunnel when riding on really rough surfaces.