Nimmers
Grand Master
Sounds like what happened to mine: https://sneeknet.io/index.php/2019/02/25/pvm-20m4a-power-supply-fault/14M4A - power IC blew to smithereens. Tube on it was great, ex ABC. I've got another 2 as backups thankfully, a 20N6U and 14" BVM whose model number escapes me.