I have one very similar. Model 6001. Its a good machine. I cleaned and repainted mine. They're pretty simple units with not much to go wrong as long as the knob switches on top are not broken.
Associated makes excellent battery chargers. They are still in business and going strong today.
Keep in mind that many old battery chargers used selenium rectifiers that degrade over the years. I prefer to replace worn out selenium rectifiers with modern silicon rectifiers. Don't be scared - it's just two big diodes and a heat sink.