Vintage Fender Jazz Bass - Pickup Cavity Brown Material

Fender made a Mocha finish around that time but it was darker than that on your bass.

I'd reckon thats a re-fin. And that gunk in the neck pocket must be affecting neck/body contact. Sand it out.

 

Hhmmm.....maybe it is a Mocha Jazz. Did you look at the wood underneath the pickup grounding plates?

 

I've never seen that before. Looks kind of like glue. My instinct says it's not factory but I could be wrong.

 

There's no evidence of any other paint in any of the other cavities? Can we see a full shot of the body?

 

The Mochas were a dark brown but some have lightened with age, probably due to the paint mix, though poly shouldn't alter when fully cured. I wonder if you've got a Friday Mocha Jazz.

 

Seems to have lost a lot of the clear poly. Difficult to tell without seeing it in person.

 

Not really an expert here but the consistency of the mocha color through the cavities and no other competing colors and that white powdery stuff (buffing compound) that seems to be prevalent in many Fenders tells me it’s the original finish 45+ years later.

The glop looking collection in the PU cavity is likely just slop. That was Fender production line during that era. As long as any excess didn’t interfere with assembly-finish, it was kicked down the line. That’s mass production 101.

Seems original to me. Looking forward to what the knowledgeable TalkBass readers have to say.

 

It's Mocha Mojo!

 

Its obviously some delicious caramel.
A little snack for the bass player with a sweet tooth.

 

If it's not hurting anything I'd say leave it alone. Don't sand the pocket too much. The stamps all appear original.

 

Don't sand the neck pocket. You'll make it far more uneven.

 

I have a 1975 Fender Precision which I bought brand new. I never really opened it up until a few years ago. The original foam under the pickups had dissolved/melted and metamorphosed into a hard plastic blob. That may be what you are seeing here. It was almost like someone had melted some ABS plastic and poured it into the bottom of the pickup cavity. WEIRD!

 

That finish is absolutely original. Don't touch the neck pocket or pickup cavities! There's no "loss" from contact between the body and neck. Sheesh.... If that were the case, every single Fender bass and guitar made between 1950 and now would be similarly afflicted. lol.

 

That’s the funk that bass has, leave it alone and rock it!!

 

I don't recall the "stick" used to hold the neck while painting leaving a masked area that looks like that.
Maybe not all the same mask line?