One of the reasons for building 'Bethesda Sidings', was to be able to run some of my existing OO stock, without having to put 'Bleakhouse Road' up, the latter being too big to leave set up at home for any length of time.

I like to operate a green diesel sequence on my layouts, so I decided to test my Hymek and Class 33 on 'Bethesda Sidings' recently. To my irritation, I found that the Heljan wheelsets didn't like the OO-SF points on the layout.

Both locos are original issue Heljan models and both had those coppery coloured wheels, on which the treads gave the appearance of being dirty. More importantly, the flanges are relatively thick, resulting in the wheelsets not running smoothly through my OO-SF A5 points, even though the back-to-back was correctly set at 14.5mm.

The solution was to replace the Heljan wheels with Black Beetle wheels, which I obtained from Branchlines recently. These are turned and have a much finer flange.

The old Heljan wheelsets were removed and the wheels pressed off their axles. I would be re-using the Heljan axles with the gear wheels on them. Both the Black Beetle and Heljan wheelsets use 2mm axles.

The Black Beetle wheels were then pressed of their axles and pressed onto the Heljan axles and replaced in the two locos.

The result was two locos that now ran very happily through the OO-SF points.

Here one bogie on the Class 33 has had it's wheels replaced:

Here is the Hymek with it's new wheels, being test run on the layout, before I replaced the bogie side frames:

Completed locos: