Jakki, the chip controls the ISCV along with other paramiters, as you have changed it that is your first port of call, who's chip is it? Is it secondhand, there is a lot more to a chip change than just "changing the chip"
get it to a specialist quick so it can be checked over properly
and whilst your on our next meet is the 9th october and I'm the new chairman
see you there

steve