I have a problem with my 73 F250 dash. When I bought it, no lights worked in the dash and no gauges worked. I replaced the I.C. voltage regulator and the lights started working as did the oil pressure gauge. Now the gas gauge,volt meter, and temp gauges are still out. I used a test light and I get a flashing light at all the gauge backs and ICVR. Also get flashing light at fuel sending unit at the tank.( I also cleaned all terminals and grounds already). Any suggestions as to what to try now and how to do it ? Thanks for any and all help offered.