This is a problem that I suspect only narrow gauge modellers encounter, when your new rolling stock doesn't fit your layout!
Having mounted 150 on its bogies I took it over to Himself's place to give it a wee test run on Dduallt.
We had an unwelcome surprise when we came to run it through Rhoslyn Cutting - it hits the bridge pillars on the engine side.
This caused some consternation, as you can imagine.
Closer examination, however, revealed there had been a fundamental (and rather foolish) error during the making of the chassis - the bogie pivots are off centre!
I have been sloppy and careless - and I've given Himself a damned good laugh into the bargain.
So the holes will have to be filled, re-drilled and the bolts re-inserted.
In future I shall remind myself to measure twice and drill once. Doh!