Replacing 3rd/high-level brake light

[ModernAndy]

I've just got a used high level brake light through the post for my mk1 Octavia. I've went to fit it and it appears to only have 5 working bulbs out of 13. I managed to get it from 4 to 5 working bulbs by jiggling the wire a bit so I'm wondering if there's something else wrong that might be the issue as I doubt it would have been sent unless all the bulbs were working. The wire and plug leading to the high level brake light look like new so I don't think that's an issue. The car does need the brake switch doing (brake lights sometimes stay on when the brake pedal isn't being depressed) and I'll be sorting that out tomorrow. It was an eBay buy and the ad didn't mention anything other than the unit being in good condition.

Any ideas?

Edited by ModernAndy on Thursday 27th October 13:21