[turretslug]

The Micamold brand 4.7nF decouplers are certainly high on the suspect list here ( not actually mica dielectric, but rather average quality paper types with a moulded Bakelite case), electrically they'll vary from quite leaky to horribly so by now. The degree of leakage also tends to be very voltage-dependent, too- a capacitor that registers into megohms with a meter using a 9V battery might be uselessly leaky with HT applied. Whilst such an ohm-meter can give a rough guide with an array of capacitors, I don't even consider keeping anything that registers even slight lingering constant reading in place for this reason. With an original AR88 (or whatever), even if each leaky capacitor only takes a small DC current, the aggregate can be substantial and make mains transformer, smoothing chokes and bias resistor chain all run much hotter than they should, not to mention extra stress on the rectifier. The Micamolds start life as flat, dry and mid-brown in colour, any that look swollen/sweaty/dark coloured need evicting pronto. The oil-filled "bath-tubs" also go electrically leaky but not often to the widespread and catastrophic degree as the Micamold types.

Some folk out there get a little over-wrought in their description of the AR88- "money no object", "second-to-none" etc.etc. Yawn. It's of commercial-market origin, a good contemporary design built to "good commercial" rather than "military" standards and some of the passive componentry is a bit average in nature, so it's not surprising that a thorough and possibly long-winded overhaul is near-inevitable after all this time.