Model railway problems and solutions thread.

I haven't noticed the existence of a thread specifically discussing problems experienced with railway models and their potential solutions. As such, I felt a thread such as this would be of use, giving useful tips in overcoming various issues arising from the hobby. For starters, I will include a (resolved) problem that I recently experienced with the Hornby 'Clan' class, so here goes!

Taken from the "New for 2011" thread:

'As an aside, and rather than create a new thread, my 'Clan' arrived Saturday, although when I put it on the track for a test run, it kept derailing on my curved points due to the lack of a rear weight-bearing axle (the new fixed Cartazzi-type contraption necessitates flangeless wheels on 2nd radius track). The loco thus appeared to 'sit' on the front wheelset of the BR1 tender, which caused the rear tender wheelset to lift completely off the track, and it was hit and miss as to whether it self-righted. It was also partly caused by excess rolling resistance on the curve caused by a stiffness in the tender drawbar.

So, how did I cure the problem? Well, after a bit of a think, I decided to disassemble the tender chassis, and found that there was far too much lateral movement on all tender axles, so I took the axles apart, and reassembled them so that the back-to-back measurement was 0.5-1mm wider than the factory setting. This cured excessive sideplay, and ensured that the tender was more stable when entering the offending curved points (I think it actually uses the frogs now!). However, this failed to stop the lifting of the rear wheelset, so I had another think. I noticed that the 'sitting' was caused by the locomotive pressing down on the metal drawbar due to a lack of clearance for vertical movement at the top. To cure this, I took the drastic step of bending the drawbar down, and then bending it closer to the pivot locating holes so that there was now a kink in the drawbar. I re-attached the tender to the locomotive, and hey presto!; a locomotive that now runs pretty damn smoothly over the offending point, and is now a prized addition to my predominantly Southern fleet. The exercise has proved so successful that it is now running better than my 'Britannia', No. 70052, which has the BR1B tender... I may do the same with that. So, if any of you are suffering from the same problem, then this is one bodge to get out of it .'