The zero button is complementary binary, removing spikes changes the
number to a higher number, but sorry I cant remember which does which.
Look at the other buttons if you have a spare zero button.
IIRC there are 2 pins at the sides, it's the top and bottm edges of those
that matter. Each edge can eiterh be straight out cut in a bit, they
operate 4 contacts i nthe lamphoder. One always operates when the cap is
fitted (this inidcates a cap _is_ fitted, removign the cap disables the
drive). the other 3 edges encode a 3 bit (yes, I do mean _3_ binary
number). In the RL's, only the bottom 2 bits are used, the RK06/RK07 use
all 3 bits (and ahve caps numbered from 0-7), I think some CDC drives
used a simlar system, but the cape was opaque and didn't also act as the
'ready' lamp.
Therefore, if you don't care abotu the cap showing the right number you
can use an RK06/RK07 #6 cap on an RL and it'll work as #2. Or you can cut
or jumper traces on the frontpanel board to fake the appopriate contacts.
But I assume the OP wants to keep his drive original.
-tony