On Thursday, April 30, 2015 at 6:47:05 PM UTC+1, wrote:

I thought you were going to say that.

PD & Ferm are/were large buyers.
Sosoco: Hi, we'd like to buy 50,000 of your grommulators. But we need you to use this grade magnet wire, that superior switch and reinforce the gears.
Crapco: Hi, we'd like to buy 50,000 of your grommulators. But we need lower cost, what can you do?
Mfrco: well, if we replace the nylon gears with ABS, use lower temp rated wire insulation, replace the plastic insulators with punched card and replace the motor with our special 5 hour life one we can do it at this price for you.

Whether the above is the reality or they're all the same we don't at this point know for sure. I've heard awful things about PD and not Ferm, but of course the sample size is too small to have any certainty.

I agree it's not conclusive that the innards are identical and you're obviously going to require a higher standard of proof than I can provide. That being the case, why are you prepared to put so much store by something you heard down the pub?