Get googling on Dry Ice Blasting, Soda Bladlsting and Corn Cob or Husk Blasting Services for wood doors and furniture... a softer version of sand blasting... mask up the neck pocket edges with duct tape... nothing to loose...
Yep thum rest off... and i'd be leaving alone... Love the bridge (if it intonates 7/10...) and Scratch Plate dink to the end aint nuffin' Coolio!
Add add the E or a new set of strings though... missing strings is takin relic to whole new level!
For Info my Entwistle JBX has 'Artec' on the inside of the cover... Artec produce pickups for OE manufacturers and by the looks of it other 'brands'...
There ya go... you did it yourself... had an issue, reached out... then fixed it yourself.
Nice... no idiot just an engineer...
Try Vol Blend Tone (VBT)...
Any trouble with strings?
Check the speaking length... Couple of old sets i had kicking about would not fit as the extra length behind the bridge sadles to the ball end block meant the thinner peg windings of the string wasn't over the nut but halfway on the 1st fret.
Choose wisely @Bassfinger...