[Ron Ramirez]

Well...don't hold back, Omer...tell us how you really feel! You do have an interesting way of holding your electrolytics in place. I chose to restuff most of my electrolytic cans to keep them looking more or less original, plus to retain the same can size to fit in the clamps.

To answer your questions...

how come you decided to change the 3A120's
Because I could.
But seriously, after over 40 years, I felt it was time to retire the original rectifiers to prevent the possibility of them shorting out at an inopportune time. Since they're new, they should be good for another 30-40 years.

how do you replace C30 (200uF) at the main switch
I haven't yet.

why do you wish to replace the TR1009 output transistors
Please read this entire thread. One TR1009 in the left channel was shorted, both TR1009's in the right channel were replaced by TR1007s. I replaced all four because one was shorted and two were incorrect replacements.

and why do you have issues with NTE?
Overpriced rebranded transistors which are not consistent in their characteristics.

One more thing. Don't forget to replace that white .01 uF 600V firecracker capacitor in your fourth photo with an X/Y rated safety cap - that connects from one side of the AC line to ground, and is an explosion waiting to happen.