E153 Transaxle Grinding when going into 3rd..was fine a couple days ago

[senn]

My E153 has started to grind into 3rd. Can minimize this with nanna shifts + double clutching. I SUSPECT it's the synchros, but I'm asking here if this is a common problem for these boxes? Has anyone done a refurb of the synchros themselves? What cost/level of difficulty am I looking at here? I'm on a tight budget (aren't we all) and would LIKE to attempt this myself, but having never done a gearbox, and not having access to oxy (i've heard some boxes require heating to get access to the inside to remove gears off shafts with pullers?) etc I'm a little hesitant...

I should also note the clutch is almost due for replacement....maybe not synchros just not disengaging properly? But all other gears don't grind soooo.....

[fixeruperer]

cant help with specific box info. but
drain the oil and replace, either with a mix of gear oil and atf, or some redline mtl or another redline oil.

drain the old oil into a clean bucket, just so you can see what the old oil is like.

sometime it can help, sometimes not. i rather try that than to rebuild the box (which it will need eventually anyway)