Hi Josef, great you have lengthened the cut to 15mm.
1/ As mentioned earlier - I really like your idea of modifying the flexible pcv by decoupling from the locating tabs and then insulating the exposed part of the pcb - completely agree this is far better than 'snipping' .
2/ blagard-01 is of course incorrect to assert that you need a jumper to connect the brown tracks because you yourself have already confirmed the system functions with two modified curved lane changers.
I assume your configuration has the following:
1/ the track is in good condition therefore all track joining connections are good from an electrical point of view.
2/ each of the two curved lane changera have exits onto different lanes in effect you are only introducimg one electrical discontinuity per lane.
3/ you are makimg use of the fact that a scalextric lane is powered in BOTH circuit directions and therefore remains fully functional when a single electrical discontinuity is introduced.
Of course there would be problems if you introduced a third lane changer into the mix - and that would be the time to each for the brown wire!!!
Enjoy the two lane changers - and your new ARC PRO :-)