I have operated Gilbert American Flyer trains all my life. The turnouts are well designed with a closed frog. They will operate for decades with no maintenance. I have taken the bottom plates off to lubricate them and clean the brass contacts. It is very rare that they need any replacement parts.
If there are derailments on the turnouts it is almost always a steam engine front pilot that needs adjustment or a supplemental spring. Also a tire can come loose from a white insulator and cause shorting or a derailment. If a derailment is caused by a turnout it is usually because the points are not held tight against the rails. This is fixed by adjusting and lubricating the mechanism under the bottom plate.
Most derailments are caused by poor track installation and alignment, especially when using the rubber roadbed. The turnout should never be fastened down when the rubber roadbed is used, just the adjacent tracks unless a proper thickness shim is used under the turnout.
