It's a steel screw going into a diecast chassis, that is two separate metals, therefore, you need to use locktite 640 and suitable activator. The main problem is the diameter of the washer attached to the screw is too large and it will not go into the counterbore in the bogie moulding. Therefore, the screw is only holding on three threads. If you tighten the screw up it restricts the movement and swing of the bogie, I don't think, with my engineering experience, varnish is not a suitable solution, therefore, I require to know if anybody has any idea what the thread is - is it BA or metric? I will purchase suitable screws and washers to solve the situation
Many thanks for your suggestion.
Suzy