Voltage is not so important as long as it is equal or greater than original part. You also must pay attention to size - new ones tend to be smaller, but higher voltages are larger, and height and diameter must fit (right diameter is more important looks wise.) . Pay attention to + and - on caps - the red leads go to a positive terminal on one, while the blue leads go to the negative terminal on the other one, and the two remaining terminals go to each other and the black (ground) leads.A very nice receiver - definitely worth resuscitating.
Also, intermittent output is probably not due to filter cap problems, but more likely dirty switches and controls, or flaky relay.
Looks like unit will need a good deoxit cleaning. Good luck with it.