I was looking today at a couple of coal side tipper wagons I bought on eBay. One was complete in the box, the other wasn’t. I found that the unboxed one didn’t tip, which proved to be due to a missing spring.
I thought it was likely that something, somewhere would have a spring which fit and sure enough, the spring from the thumbtack coupler proved to be just right. I have a couple of damaged boxcars bought as part of a job lot, so now we are tipping on two!
