The manual / remote button only turns off the remote receiver.
The on/off relay is on the micro board. Its the white square one beside the fuse. Relays also like to get cold solder joints on many brands.
For reliability 90% of fails were on the HV/PS board. In the states this
style chassis was the best selling TV of all. About 1 in 4 sets. It came in 13"
17", 19",23" & 25" screen. I still have a 13" I got new back in about 1980.
Never broke down & still works great..
73 Zeno
LFOD !