The repair & restoration of this Hofner Senator turned out to be a little more complex than I had expected.
The electronics were not working, the neck was warped, the top was lifting away from the body, some of the binding was missing & other pieces were hanging off, the string nut was broken, the scratch-guard mounting was broken off, & a knob was missing.
It is all back in playable condition now.
One of its problems was that the electronics did nothing but buzz loudly.
I discovered that both control pots were partially seized & so needed cleaning out & lubricating to get them working properly.
Also, at some time somebody had replaced the output jack but wired it up backwards, an easy thing for me to rectify.
The pick-up though was totally dead.
With the cover off I couldn't find any bad connections & so the only option was to rewind the coil.
After totally stripping down the pick-up & removing all the original windings I could see that the plastic bobbin had distorted & squeezed up on one side. That could make the rewinding task a bit tricky if the very thin & delicate wire were to catch the edge during the process. My solution to that was to push a spacer into the gap & warm the bobbin for a while under a 100w spotlight. It worked & after about 20 minutes the bobbin had reverted to its original shape & so rewinding could begin.
Like most luthiers & guitar techs who only rarely need to rewind pick-ups, it is not worth me spending £350-£450 on a rewinding machine & so like others I made my own out of bits & pieces I had around my workshop.
It is powered by my variable speed drill. The bobbin holder runs in 2 deep-groove bearings to ensure spinning accuracy. There is a magnet in one end of the holder which trips a reed switch once every rev. The reed switch is wired into the '=' button on the circuit board of an old calculator & so counts the total number of revolutions, 4750 revs for this particular pick-up.
The bobbin was rewound with 43awg/0.056mm polyester coated pickup wire & then wrapped with red tape to match the original before being re-assembled.
The pick-up & controls tested out ok & were now ready to go back in the instrument once I'd completed all the other jobs on it.
I glued the top back down before re-attaching the loose binding. One section of binding had to be replaced with a new piece & I aged it by wiping it over with some amber coloured lacquer.
The string nut had broken off at one end & couldn't retain the top string in position. I made a new replica one by laminating together some black & white strips & then shaping it to match the original.
The scratch plate required me to make & attach a new mounting block on the rear to stop it waving around.
I made it from some similar faux-tortoiseshell off-cut material that I had left over from a previous job.
Straightening the warped neck took a week. I clamped it to a straight edge at both ends & kept it under my 100 watt spotlight to warm it, whilst each day gradually tightening a centre clamp to pull out the bow.
Then a fret dress to level & remove all signs of wear & get them looking like new.
A slight mod to the bridge to get the action height set correctly then a new knob & a good clean up plus some new strings.
Et voila! Plug it in & make some music.