Notes on power: 50 watts isn't a huge difference from 70 watts. To go twice as loud, in watts, you need ten times the power. Vintage receivers tend to have more grunt, more available solid power than the more recent A/V & home theater jobs, which are infamous for manipulating their specs to make you think you're getting a receiver that could summon Poseidon from the bottom of the ocean but in reality will barely put a ripple in your tea cup. Having been a collector of hi-fi for the last ten years, I can tell you it is extremely rare to find an untouched vintage piece that's going to work flawlessly without some servicing. It may be fine for a few months, maybe even a year or two if you're gentle, but one day you get up to hear some Marantz 2230 magic and, wtf, why is it doing that? It wasn't doing that yesterday. You open it up, clean the controls, and that seems to take care of it, but it comes back a week later, and soon you can't stand listening to it and begin your repair journey: do I send it out? Do I take it somewhere, if such a place exists near me? Do I try to fix it myself?
It's not unlike owning a vintage sports car; at some point, it's going to need some work to perform soundly.
Your safest bet is probably buying from someone here at AK, who will be honest about the condition of the piece and whether or not it's truly been "serviced." For something to be truly serviced, you need a master tech with a scope, signal generator, etc. who can bring the device back to factory specs. People at AK tend to care enough about their equipment to have this done or are least far more likely to have done so than sellers on those big public auction sites. Just my .02.
By the way, my kid and I love Beaker!