Not been used for perhaps 8 years, tested numerous times previously in
use, all fine.
Go to use it again, push the test button and flash and a bang.
The 1/8 watt dropper that is switched in on test, connected to supply
side (240V here), partly burnt up and burned up thin traces.
That 1/8 W presumably MO resistor now measures about 1.8K, residul green
and brown bands, as 30mA trip, presumably was 510K.
Would there be metalisation creep associated with a MO resistor? or how
else could a MO resistor initially fail by "losing" ohms?
Obviously it would not have dropped to 1.8K in storage, just low enough
to overheat during half a second or so of powering, then runaway/sputtering.