you are right, my Dips toggle when they want, i have follow members idea : check with multimeter and boot SFII Rom test.I bet your switches are flaky. Several of the DIP switches on my A board were corroded or worn out. They did not make good electrical contact. I replace all three switch blocks and now the DIP switch settings are working a whole lot better.
I had flood all with electronic cleaner spray and order some new "piano type".
Time to service my A board...
thank you for any response.