Hello All,
I have found a replacement for the fiber washers (29-7971) used to seal the engine oil banjo at the bottom of the oil tank on my bike ('70 BSA Starfire). I found some drain plug crush washers (22mm ID x 30mm OD) on Amazon. They work well - no drips, drools or leaks!
There may be means of living with the fiber washers, but the crush washers are set-and-forget.
Oliver Pi