Nice one Chong! Be sure to treat that puppy to a pair of brand new valves / tubes... open her up and check the capacitors for bulging... also check the bottom board around the transistors... if the amp has been left on 24/7 for years there will be signs of browning on the PCB under the transistors... this is more indicative of cheap PCB than it is anything else.... if there is scorching then check the pads on the underside of the board as these become very brittle and can lift.
Hopefully you've got one with a nice "white" PCB
Other things to look for... check the RCA quad socket, sometimes the ground pins snap off... also check the valve sockets, grab one with your hand, turn the board over, start rocking it and make sure the solder joints are not moving... it is ALWAYS a good idea to reflow the joints on the valve bases... people who have rolled a lot of valves over the years find that these joins actually seperate (well, I tell them to look there!) and they have intermittent "crackling" problems... it's simply the joints which have become compromised.
Another thing you can do is get a pin and gently lever the connectors inwards on the valve sockets... this will tighten the grip on the valve pins
If you are going to use the stock valves for a while then remove them and get some 600 grade wet / dry paper.... remove the surface oxidisation from the pins, this helps.... I can tell you this for a fact, I have measured plenty of valves on my tube imp analyser, a simple cleaning of the pins can change the readings.
Best to go with the 6N23P-EB for starters, it's the best allrounder IMO (best VFM, very robust, long life, superb SQ) and it has chromed pins so no worries about oxidisation.... built like tanks and stay in spec much longer than the 6922.
You can lose the 10uF input caps, just jumper across the pads... if you want to keep them then replace them for non polar types. The 220uF non polar ouput coupling caps can be replaced with 470uF or 1000uF non polar types (nichicon MUSE are good) this is a good idea if you are using low Z 'phones.... enter your headphone impedance in the "resistance" field and your value of output cap in the capacitance field
www.sengpielaudio.com/calculator-RCpad.htmAll the best,
Mike.