Congrats on the 2245. I will bite on this and tell you what I do when I get a new piece of gear. I do usually update it but they do not always need it right away.
First this is a great reference right here for solid state gear. This was writen by EchoWars a real expert and fountain of knowledge here on AK.
https://audiokarma.org/forums/index.php?threads/amplifier-distortion-dc-offset-and-you.5634/
Next thing is get the service manual for the 2245. Very easy to find.
http://akdatabase.com/AKview/displayimage.php?album=1&pos=80
Can you work on electronics? Have a willingness to learn? Do you have a digital volt meter at the very least? That said if its working and sounds good after and hour or so its probably fine. Below are just a few things I check out with a new piece of working vintage gear. Everybody has there own thing and there are real experts that will chime in but this has served me well over the years. That said I do usually update my units I get if they are ones I am keeping for my personal collection. the 2245 is one that would be very worthy of this and is relatively easy to work on.
Take the cover off the bottom if you are comfortable with this. Look at the boards, amplifier modules, power supply (board with the clear plastic realy) does it look good? Any of the capacitors have a covering that look like they have shrunk down from the top like it has been subjected to lots of heat? Anything look burnt or like it has been running hot?
First thing I do is check the voltage coming from the power supply board. Does it jive with the service manual. If not its easy to adjust if you are confident working on live elctronics. Dont do it if you are not.
What kind of voltage are you reading at the speaker outputs, set your meter to milivolts DC and check it. Hopefully it is close to the service manual, if not it is easy to adjust if you are comfortable doing it. If it wont adjust there are things that need to be updated. That said after say 20 minutes feel the main transformer, the two big filter capacitors next to the transfomer, the heat sinks on the amplifier boards. Are they cool to the touch? Both amp heat sinks the same temperature? Unit sound OK, all the different inputs working? Background quiet with headphones and the sound balance equal on both sides?
If these check out its probably fine in the moment. That said updating down the road will usually make it sound even better. Not always but in most cases.
These are just some suggestions that have worked for me and I know enough to be dangerous.
Many far more qualified members will chime in with more suggestions but read EchoWars exellent sticky about amplifier adjustments.
Post some pictures when you can too with it opened up so we can see if there are any areas of concern etc.
