In case there are any valve fundis here who don't browse the DIY section, please see my question on a dodgy FM stage in the old Philips radio I am restoring (or at least trying to ):
https://www.avforums.co.za/index.php/topic,70131.msg887627.html#msg887627
https://www.avforums.co.za/index.php/topic,70131.msg887627.html#msg887627