[Arran]

Mike;
I would have a looks on what we call "the barking dog forum" or Antique radio forum, before you toss the original vibrator, there are a lot of different circuits for solid state substitutes, some are much better then others. It may also be possible to revive the original vibrator by dismantling it and polishing the contacts, which are often fouled by off gassing from the sponge rubber insulation inside, but have no other problems. Mechanical or solid state vibrator or not you will need to replace the 1500 volt hash capacitor or the vibrator could be damaged.
As for testing condensers, if they are obviously paper, inside a cardboard tube, if they are not bad now they soon will be. If they are ceramic disk condensers, or molded mica leave them alone. Electrolytic filter caps may work for testing, if they are not shorted, but should be replaced if the radio is to be put into service.
The radio in your New Yorker is probably similar to the one in my Imperial, where the tuner section is separated from the power supply and audio amp, which has the speaker mounted to it. The amp in mine has a pair of 6AQ5s so probably has a decent amount of audio output, as well as decent fidelity, I haven't got around to servicing it yet.
Regards
Arran