wow that brings back memories,
my first bass, that I taught myself tp play on, way back in the 80's was a red ET-280 exactly like yours.
it sounded like crap, had a neck like a sausage, and was made of some kind of pine/concrete hybrid.
but it stuck with me, as my spare when I was gigging, and as a loaner once I started teaching friends and family how to play, and my first attempt at customisation was stripping the body back to bare wood and varnishing it.
Now I am teaching a bit at the school where I work it came back out of the loft again. while I was trying to set it up for a lefty to use I made a revelation. as stock the bridge was in the wrong place! by dropping it back 2 inches it stopped it sounding like a rubber band ,
I also took a plane to the neck and reprofiled it and suddenly it was a dream to play
unfortunately the only surviving pickup stopped hearing the A string, and when I stripped it down to find out why ,the electrics disintegrated in my hands. the plastic round the wires literally turned to dust.
as the weight is also an issue(I cycle to work with guitar and bass on my back) my plan is to replace all the hardware, chop most of the body off and make myself a very original 5 string travel bass.
so further to that, Slotrod if you want any of the original parts I have gutted from it, they're yours for the price of P&P. There's a single pickup (plus cover), bridge (no cover unfortunately), machine heads, scratch plate and pots/knobs. the nut unfortunately is not original, in fact it is a repurposed guitar nut that was on it when I inherited.
cheers
Red