1974 (June) Rickenbacker 4001 :: reglued loose binding, replaced broken “wavy” Grover tuners with Hipshot HB5’s, installed Schaller strap locks, dressed the worn saddle slots, new Bakelite nut, new string damper pad and a push-pull pot for the bridge pickup.
The 4001 has a 0.0047 µƒ capacitor (not your standard 0.047 µƒ value found connected to the tone pot) in the bridge circuit that cuts bass frequencies and the overall output. The push-pull pot gives the option of removing the cap from the circuit for increased volume and fuller tone. I highly recommend this mod as it gives you a lot of tonal options.
Note: Those looking to do this bridge cap bypass mod - Rickenbacker sells a shorter 330kΩ push-pull pot that they use on the 4003. Other push-pull pots (Alpha, etc) are often too tall to fit in the control cavity without modifications. Always think twice before permanently altering your vintage instruments!