1. Is this a post,war or remake?
2. Magnetraction also needs a frame magnet near the motors field coil and wheels, the metallurgy of parts is different on these motors. You can use parts for or from a normal motor at times, but to skip a magnetraction part would cause failure of the feature if equip. E.g. left and right axle bearings for a 2037 are different metals. One side is ferris the other non ferris. Ones for a 2026 fit, but they are brass/bronze and the magnetraction's natural polarized field will be " shorted out", severed, etc. if used.
3 Which GG-1 ? (There is a lot of history on the real ones. They ran for 50 years, famous designer, fast & strong enough to snap couplers from a stop.)
A traction tire version? The geared side? Blind wheel?
And if not the traction tire version, how will this solve the problem? That's what I don't get.
4 The thing is likely tripoding; tipping on two diagonally opposed wheels, resting on 3 wheels. Or, It may be the base, table track flatness, or the table. Tweaking a sheet metal frame slightly may true it.
On something new I'd have no clue on how to do it offhand.
Checking table rails for gauge and tops for flatness and that there is no twist to the flat plane, should be done too.
(Straight edge or glass/plexi with plasitigauge or blueing, crayon on paper, etc for a rub test)
Any shoe you add should tip the thing towards traction side(they push up)
Or use a wisker pushing on rail side (vs up) or even wheel flange wiper or 2 rail plunger if you suspect ground loss at the axle.
I've used bell wire for a number of whisker pick ups. A pen spring can made into a holder for quick swap outs and flex; bell wire bent to an L, or heavy household solid wire as a wrap mount.
5. It needs a better bearing? If the axle hole is sheet metal without a bushing, the weight is not spread out enough, excess weight is making the sheet metal act like a brake shoe (likely on a roughed and worn axle journal area too). Or the bushings if there need replacing, flushed, etc. Adding bushings or bearings if there aren't any should lessen resistance to rolling heavy.
Ffinally; on hand (?) traction boost: You may be fine on using just one side for power. Try some two sided tape,on one rail. It will mostly vanish from sight and provide a definite grip, lasts a long time too, like years while helping a Virginian rectifier's (another cool electric) coal drag up a 5% grade 2- 3 hours a week (You may want to detack the upside with fingers, some dust, etc. as they are very sticky at first. The texture alone is great traction.,Removal and replacement isn't hard. The stuff for window sealing plastic is the right size best texture, rugged, etc.)