I am running two 999 engines that I received new in 1949 and 1951 and they seem to be the same bulletproof material as the 666. Gotta love those Marx.
Yus! 
Mitch
Marx was very good at using what they already had to make other things. Those little motors just keep on running.
Today’s designers should take note of what Marx did and reuse as much as possible, what they already have.
Nothing runs like a Marx. I have pulled motors out that looked like death eating a cracker, and with a little clean up, they are off to the races! I doubt much of the equipment being made now will stand up to the test of time, let alone playtime with kids! [(-D]