Mx125 sub

Question

I have a MX-125 sub that is not working. The amp is powering on but it creates strong feedback off and on especially when the bass level dial is adjusted and does not produce bass. Prior to it stopping working it used to produce a lot of hum. This sub was purchased in 1997 and stoppped working around 2000. I put it away and just now decided to try and get it fixed and found out that M&K is out of business. The amp circuit board is PN 34240D. Any help or advice on getting parts or service would be appreciated.Richard