C350 i have today fixed one a 49 capacitors replaced because the blue JH capacitors are most of them bad (if you have a no-lie capacitor meter) you can measure the difference .
the most blue 10 uf 25 volt replace for new and also the 47 uf and 25 volt ones there are also some modifications to do there is one place with a small black ic there are 2 capacitors on and one of them is 33 uf 50v change to a radial elco 47 uf 100v position is C146 and the other capacitor is 4.7 uf 50 v to replace for the same or higher voltage , in this days the c350 is an older amplifier and knowing that the most capacitors are have most 63 v as the littlest to get in shops so its always to have enough voltage tolerance on the capacitors and the format size is the same as the old 25 volt ones of the used capacitors from the early years 2000 . special the Korean made ones have had much problems.
Replace all old blue old JH capacitors they are deformed and are not self-healing anymore. to wait sometimes one hour to get from the protection mode is not the way for the Amplifier.
Also the gread purple NAD capacitors those can internal rattle like a baby rattle old and dried as the ones you see on the picture . the only 2 jh capacitors that are good on the amp i repaired where on the volumepotentiometer .
The other brands little elco's 50V can maybe have a longer health but this on the picture are all the JH ones and are replaced that i today have repaired that amplifier is now in good condition again. i have token simply philips 2200uf 63 volt to get that amp first working again , and that was what it does now later maybe F&T capacitor 2200uf 63 v after a while for little better sound.
But a good capacity meter is necessary with no lie detection because a simple meter will not have a secure range, there is also a 560 ohm resistor that must changed for 560 ohm but a 2 watt type (fusable) position R227
On the bridge cells there are ceramic capacitors used c511 until c513 that 3 must be replaced by polyester film capacitors 100nf /100 volt i have used 3 axial ones
Change D309 and D310 from 1N4148 to 10M Ohm 1/6W 5% Metal Film Resistor to get a better balans on low volume .
Maybe you will find the next modification already or not
Change R401 and R402 from 2.2 Ohm/2W to a jumper wire
Then beware to do a very secure soldering of every component because a soldering failure with adjacent components is easily made. and sometimes difficult to find it back.