This might be of some interest to the 'neanders.
About 10 years ago my brother gave me a push screwdriver. It says "Craftsman" on the wood handle and "Craftsman West Germany" on the metal. Like new and in perfect working order. Except it had no bits. None. Over the years I've threatened to grind down some 1/4" bits to fit or make an adapter but it never happened.
Then the Lee Valley catalog happened (how did those guys find me?) and I found "hex adapters for Yankee screwdrivers" in it. I ordered the 5.5mm size as that was the measured diameter.
Got it and it slid right in. The end where half of the shaft is cut away fit correctly. The notch that the retainer locks into... was in the wrong place.
I could have sent it back and gotten a refund. I'm sure Lee Valley would do that. And then I would have a push screwdriver with no bits that hadn't been used in 10 years. And counting. The adapter didn't go back.
I cut a new notch using my favorite layout dye otherwise known as a Sharpie and a Dremel cutoff wheel. The new notch is a bit over 1/4" away from the factory cut notch. It works perfectly.
Like I said the screwdriver looks like new, a problem I intend to fix shortly. A perfect teammate for my Yankee drill.
-Tom