No need to replace the MB! Send it to Acill here on this forum, you will get a fine MB back.
He's in California but sometimes has to travel so it may take a few weeks.
I will be sending mine there as soon as I get this old Marantz receiver off my bench and have room for disassembly. First the A2000 then the 4000T. Hope you have a rev 6.2 or better.