Terry,
I replaced the switch on my TU150FD about 6 months ago. I ordered it online thru Yenibiz.com - they're in Belgium. The switch for my tractor has 6 posts - the replacement has wiring instructions for 3 of the 6. It took me a couple of hours to ascertain the postion for the other 3. I got lucky the first try.
The reason I mention this is because the replacement is not identical but it's close. The markings on the back of the original switch do not correspond with the back of the replacement. I did keep the diagram.
Slight modifications were needed for securing the wires to the posts of the new switch.
There are probably other places to get a swich but I was ordering other items as well. I was impressed with the web site and the amount of Iseki replacement parts. I did check with a tractor company here but the price overseas with shipping was cheaper still.
Yell if I can help.