hi ive got issues with the triggering on my 453,firstly it wouldnt trigger on ch A or B,i washed the whole scope down in the shower and dried it,it now works fine on ch a but has a hard time triggering on ch b,its odd if i remove q454 and q 464 it makes no difference,the displayed waveform is very jittery but sort of triggers,the level control seems very sharp on chB but normal on ch A,any idea where i start looking? q454 was dead so replaced it but made no difference i suspect a cap ,Its a later scope with the fet front end.