Vintage 70s Rayovac Sportsman 3,4,6 or 7 D Cell flashlight

Just taken delivery of a vintage 70s Rayovac Sportsman 3,4,6 or 7 D Cell flashlight from eBay Germany:

http://www.ebay.co.uk/itm/322417453363…

Though it’s in near new condition, it won’t switch on. I’ve put in new D cells, tried various bulbs inc LED, all the obvious things. So guessing it’s a continuity problem. When I was getting the lens back, the thing flashed on for an instant. All ideas to get it working are welcome. Cheers!
Best regards
John

I think the most likely issue with this will be the switch.
The contacts tend to get oxidized or worn or both.

Thanks, will try that

after a good cleaning and lube job try bending the contact spring so it makes more forceful contact with the inner ring of the head between the bulb and the switch. works like a charm on mine. WD-40 and an air compressor can make an old slide switch work like new again.