[RojDW48]

I don't have the extensive knowledge of previous posters but I have carried out simple repairs on both of these amps. As advised - keep it simple, track down faults, repair them one at a time and listen. They were well designed and that means reliable and long lived. Use a known, trusted source (not the point one pre-amp). That will be separate issue. Very few valve pre-amps from this period survived in good working order - as opposed to most power amps - feels like another thread - someone will now tell me it's already been done!