Not sure where to jump switch

[appleTXOpaque]

First time solder/desoldering and lubing keys. Up arrow, Home, and End keys no longer work; my concern mostly lies with the up arrow key. When I touch Red A to Yellow B, the keyboard tester registers the correct input. Soldering a jump between those 2 did not work; I'm wondering if I'm supposed to solder Red B to to Yellow B? Touching the B pin to anything did not register any inputs.





Also, I noticed after soldering Red A to Yellow B, touching the Red A to the other 'A' pins (eg the left pins) for the Home + End keys registered them as the correct inputs. So I'm assuming I would probably have to jump the entire column's 'B'/right pins to each other to make it work? Thanks in advance.

[suicidal_orange]

This stuff is very hard to talk about but if touching Red A to Yellow B types up (the "correct input"?) and you solder that connection you're effectively holding the switch down, so you don't want to do that.

Looks like a Filco matrix and if it is your suggestion of B to B would be what you need to solder, if the red B pad of up is damaged you may also need to connect it to the B pin of End, then Home should come back to life too.  Solder one jumper, test, only solder more if keys still don't work

[appleTXOpaque]

This belongs to a Keyed Up Labs (KUL) ES-87; will try your suggestions and report back. Thanks so much!