Just to summarise... and then an added one further comment...
Arc Pro power base is reported to be incompatible with curve lane changers due to the base providing separate power to lanes 1 and 2 while unmodified curve lane changers assume a single power source is used to power both lanes (and were originally designed to comply with that spec). To achieve compatibility therefore requires some kind of modification/s with each approach having various trade offs. Prima facia there are three main options:
Option A - modify the Arc Pro (not recommended as would void warrantee)
Option B - modify each curve lane changer (as proposed above on this forum)
Option C - modify the standard track pieces either side of the Arc Pro power base as per my earlier post (agree this would not be compatible with analog mode but easier to implement if you have a lot of curve lane changers i.e. 3 or more)
Returning to option B for some lane changers (the latter ones where the olutput ‘wedge‘ is fixed in the centre position rather than free to move) i believe there is a simpler alternative to the earlier recommendation to create 1cm dead spots on BOTH rails at the centre of the cross-over lane. For this specific version of curve the output wedge is itself a dead spot - hence only require to create a single dead spot on one of the cross-over rails at the point where it is directly opposite to the ouput wedge (I.e. opposite a dead spot which is already present in the design). This achieves the same effect but half the modification work involved - also, a car switching lanes will only experience one period of loss of power rather than two. This approach will require a bit of care doing the ’digital’ to ‘analog’ mod to ensure the cross over lane itself remains powered. Again 1cm should be fine when adding the dead spot. For the avoidance of doubt, this approach should not be tried with curved lane changer where the ouput wedge is of the earlier ‘floating’ type.
I believe maintaining maximum compatibility across all scalextric parts (whether current or obsolete) will help everyone get the maximum enjoyment out of this amazing hobby... hence all of this discuusion about compatibility is well worth the effort. Thanks forum colleagues for all the enthusiasm, interest, and proposed solutions - we now have plenty of workable options :-)