Vintage Synth Repair

>>I have a MK 1 notron, grey, serial # 10009 (does that mean #09?) ...
> Bought it off ebay for 850$USD... .....element 4's F5 knob is a
little hard to turn .......How do I know what operating system is
inside?<<

ok, first y'r 104. you are probably looking for a fault with one of
the 1458 op-amps (top right corner of the schemo) where the range
switches are, & where the column output is buffered. it's extremely
unlikely you have a fault before that stage that affects all of the
steps of the column. I think the 104, along with several other simple
step-sequencers of that era, used 12 steps rather than 16 because the
12-way switches were easy to get. the actual shift-registers are three
lumps of four, & it wouldn't have killed them to add another except
for trying to find a 16-way "last step" switch.

y'r mk1 notron is indeed an early one, & that's an extremely good
price- they have gone for three times that much in the past. I don't
know much about the subsequent software versions- I ignored the mk2
when it came out, thinking it quite hideous, & then lost touch with
dave & gerard. tom moravansky on the notron list (amongst others) is
the expert here. mine is cut open because I moved the "write" switch
to the rear of the case after one or two accidents... & as I
mentioned, it is in bits now because several of the tiny switches
failed. I have been contemplating mounting it on a 19" panel, & got as
far as having one made & buying 100+ mini toggle switches, but now I
have an octopus & it's making me think that the tactile nature of the
notron is too good to abandon. besides, I can probably get new
switches for it. 
one of my encoder wheels binds against the case slightly- maybe that
is the problem with yours? or against the mounting bracketry inside?
anyway, a failing encoder would usually manifest itself some other
way- it's unusual for them to fail by getting stiffer.

let me know how you get on with the roland, eh? :-)

duncan.