Hi,
Sorry for the tardy response...
Yes it was without a doubt the copper injector seals that were the cause in my case. Take great care when reassembling, the sealing faces must be clean and take extra care not to nick an o ring when refitting the injectors. I had a large CO2 fire extinguisher to hand when started for the first time after rebuilding. I figured that dumping that into the air intake would stop a runaway. As it was all was well,
Good luck,
Mike.