I sold one of these on eBay a while back, I bought it new in the 80s and only got it to work as expected once. The person I sold it too was able to get it working and said they are having a blast with it.
munksbeer, please have your child evaluated by a developmental pediatrician. It will take a number of visits and if you are in the U.S. and it will most likely not be covered by insurance, but it is vital in helping you get the support your child may need. I am autistic and so is my child, growing up was hard for me and it is hard for my child, but we are able to provide them with a lot more understanding and affordances to make their life better.
A Herman Miller Aeron, Mirra, Cosm, or similar can usually be found at a liquidation company for a lot less than retail. Keep in mind that they are repairable and parts are readily available, there are not many other brands that have that kind of support.