Cool you came across a NOS Pioneer receiver......wonder what the price was for it 35 years ago....
According to ClassicAudio, it was $339 MSRP.
http://www.classicaudio.com/value/pio/index.html
I agree, the SX-828 is a bit high, but it all depends on where you are for price.
I've found the 70s vintage Pioneer tuners to be the best.
I personally like the early 70s ones. (SX-990, SX-6000, SX-9000, etc...)
Living in an apartment with a fire escape makes me think of high density urban environment. Inner city? It may be that you are just in a bad spot for signal. Lots of metal around does mess with signals.
If you can get an antenna up on the roof would help...maybe. If you are in a short building surrounded by tall "sky scrapers", you may be just screwed.
FWIW, a lot of people pop in here and think they hit gold because they have what they think is an NOS unit. They usually don't like what they hear and leave. Turns out you are not one of them.
I've found that its more of a "luck of the draw" thing with vintage units on which ones have really good sensitive tuners. Not so much by make and model. Most work pretty well, but some have issues. They work but not really well.