'BomberH' there was a time in the 1980s when it was discovered some (a half dozen or less) Escapac ejection seat tubes had been manufactured without the tube being drilled out. Story here:
a4-glider | A-4 Skyhawk Association
"...Another Postscript; As I was going through my relight procedures and glider training at Cecil, over at Pensacola, the Paint and Return facility (PAR) or SDLM folks were taking a A-4F out on an ‘acceptance flight’. The A/C didn’t make it back. The J52 P408 engine stopped for some reason, and the acceptance pilot tried to eject and the seat didn’t work and the results were fatal. The wrecked A4 was shallow enough that it was salvaged. They found the pilot still in the seat with the canopy gone. Seems the SS steel tube that runs from the seat initiator to the rocket motor wasn’t a hollow tube. The middle section was blocked, not drilled out. So for this test pilot, the canopy fired but the seat didn’t. Ouch.
NavAirSysCom checked the rest of the A-4 fleet and found 5 more A-4’s with the blocked seat rocket initiator tubes. Yep, you guessed it. MB 12 was one. Had I once looked at the fuel gage and saw zero, I would have ejected. The canopy would have come off and the seat would have stayed in the Aircraft. I wouldn’t have made the end of the runway and the wreckage would have burned...."
For those interested this incompletely drilled tube may have been resposible for Ralph being unable to eject from 879 (in 1974) but we will never know. This was not an issue for the RAN FAA by mid 1984, I guess the Kiwis checked it out etc.