I used to use the mts3 with the 55015p, until a few months ago.
Certain locos,of which I have not made a list, have lights that work in dc, but not in dcc with the 55015p.
(I now have the central station 3, so i know the lights work digitally.)
Theres nothing wrong. “9” doesnt always activate the lights with the 55015p
It depends on the loco./board.
I have the alexander theisen sachsen iik, no,lights, yet, black DR toy fair edition, lights.
Sachsen ivk, vik, austrian center cab diesel, newest orange jack rod switcher, older mts and brand new mfx moguls, all good.
Being absolutely clueless about addresses, dcc, and of course, life, lol, i assume, simply, that certain early boards dont link lights to “9”. Not a solution, simply to let you know my experience. Nothings amiss with the loco or handheld.
As for the bars, they should be the same size, i believe. i don’t know if it matters, so long as they make contact. If your loco is operating properly in dc, that indicates the difference in size isn’t an issue.