I have a 2007 Triton Tr21xhp that Triton sent a new tachometer to me for, it has an ',05 build date. , It has been installed but when running for testing, the tach reads but about 2000 rpms too high. , I believe it could be that the switches aren',t set for a Mercury engine. , What are the proper switch settings for the gauge on a 2007 Mercury 250 ProXS?