You should check out c15 cap is a 47n class x probably a 270volt stock, is under speck, there is a 310 volt measuring over that cap you could replace it with a 400 or 630 volt one.
Right now it's necrophagia bleeding torment, on the radio, it's from Monday to Friday at 21h to 22h hard Rock and heavy metal from 1970 to now. Next is Joel hoekstra's13 ruining games finish line, and so on.
All the Vietnam made dsl have the same problem, i have the 100h just the same flub on the ultra gain, so what i did is to bypass a capacitor, on the 100h is c18 on the 100hr is c72 it should reduce the flub very much.