I got one about ten years ago from some one on audiogon. He had recapped it audiophile-style, but there was a hum I could never trace until I found the original assembly instructions on eBay. Not only colour coded schematics but colour illustrations. Comparing it to my amp I discovered a shielded input wire from the rca’s to the front of the chassis had the shield soldered at both ends to ground. The manual had it soldered at one end only. I severed the connection at one end and no more hum.baffled two techs I had go over it.
Easy to cut a aluminum panel for the bottom...i did sheetmetal for 3.5 decades...and plastic/wood too... Go to a sheetmetal shop with dimensions if your unsure of what to do... You can cut it easily yourself...too...if you are skilled
