Aiwa C30 recap and OP amps

Hi Guys,

after recapping and OP amp rolling from the stock 4558 to NE5532 with minor changes of caps and some resistors on Toshiba SY-335 I'm working on a little Aiwa C30 preamp that I'm using in my bedroom setup.
Caps are replaced 1:1, sockets for the OP amps are in and the plan was to replace the 4558 in there with NE5532 like I did with the Toshiba but the line stage is oscillating at 500KHz. The Phono stage seems to be fine with the 5532 and is quiet. I put the old 4558 back in and it runs OK but the NE5532 was giving the TOshiba so much more life that I was hoping to do the same with the C30.
Unfortunately I can not locate any schematic for the C30/50 or similar on HifiEngine. Can you guy help out here?
What I found is that Aiwa did not bother with bypass caps at the OP amps locations, maybe that is the missing link. Does anybody know of mods that makes it easier to change the OP amps to more lively ones?

Thanks

Axel
 
Because it was cheaper to manufacture at that time. Why Toshiba chose the same?! It all comes down to money.
I'm not questioning thei engineering/accounting decisions of the time, I try to mod it and make it better. The Toshiba in my living room setup got better, so why not attempting this here too?