I got to finally use my new Rapala HD electric knife last night. I had a new unused set of 6" blades from my old knife
I wanted to use them for the ribs. However they don't lock in. They are identical except for a hole in the new blades.
You can't use the old blades with the HD motor. Thumbs down on that. Other than that, I'm liking the extra power so far.
The blades are hardened steel and the hole appears to actually be egg-shaed, not round.
So drilling yourself might be tough.
Dremel??
Take them to a small local machine shop.
I'm sure they could help you for a small reasonable price.
Doesn't cost a dime to at least ask.