Going through the same process with the GWR Castle Class by Peter Rich.
Just correct as you see fit, modifying the easiest part to alter further down the line, in case this change causes another problem.
Also triple check everything around any issue you find, before modifying parts, as there could be an accumulation of small errors in other area, causing the problem (in your screen shot, there is also interference between the Crosshead slot and Connecting Rod side face).
For the 1/32" interference:-
Is there an offset in the Combination lever and if so, have you modelled it in the correct direction, or possibly mixed up the LH and RH parts in your assembly?
Nick.
Edited By Nick Hughes on 15/01/2023 14:08:01