I'm not professional but after research looks like it's time for vacuum tubes replacement or in good case bias setup. I found only small vacuum tubes for replacement they look like new ones his old stock. A pair VTL Deluxe 225 Monoblock Tube Amplifiers. Four small old stock, new or used ones (I'm not sure, for me they look like new) vacuum tubes. Both of them packed in original VTL boxes.
The item "VTL Deluxe 225 Monoblock Tube power Amplifiers (Pair)" is in sale since Sunday, September 8, 2019. This item is in the category "Consumer Electronics\Vintage Electronics\Vintage Audio & Video\Vintage Amplifiers & Tube Amps". The seller is "mcmk2" and is located in Los Angeles, California. This item can't be shipped, the buyer must pick up the item.