M 122: convert two keys to two-row vertical key

[feltel]

After sorting out my Teensy-related problems I'm now in the process of completing my Model M 122 keyboard project. On the numpad I'd like to convert the two keys above the enter key to a single two-row Plus key as it is standard on a regular Model M. Therefore I obtained a plus key and a white vertical stabilizer insert. It looks like it is not enough to remove the spring to install the insert deep enough into the barrel frame. So I have to remove the hammer also, which is only possible by doing a bolt or screw mod? Is my assumption correct?

[fohat.digs]

After sorting out my Teensy-related problems I'm now in the process of completing my Model M 122 keyboard project. On the numpad I'd like to convert the two keys above the enter key to a single two-row Plus key as it is standard on a regular Model M. Therefore I obtained a plus key and a white vertical stabilizer insert. It looks like it is not enough to remove the spring to install the insert deep enough into the barrel frame. So I have to remove the hammer also, which is only possible by doing a bolt or screw mod? Is my assumption correct?

That's right.

And I'm pretty sure that the vertical Unicomp insert is black and it is the horizontal one that is white.

[feltel]

Yes, you are right. Damnit. After cross-checking the Unicomp website again a black insert is needed for vertical keys. Putting it to the wishlist for the next Unicomp order to come. 

[E TwentyNine]

It looks like it is not enough to remove the spring to install the insert deep enough into the barrel frame. So I have to remove the hammer also, which is only possible by doing a bolt or screw mod? Is my assumption correct?

Not entirely.  I messed with this once years back, but it was not on a keyboard I was using for anything more than a week or two.

If you trim down the peg on the key, and cut the insert so it doesn't extend as far down, and just pull the spring, you can do it without a bolt mod.

The pivot plate is still there of course, but in the time I tried this I didn't have an issue with any random presses.  And or course if you have it set up with a teensy you can just map that key to nothing.