Any electricians out there?

[The Grizz]

Check the end caps for black burn marks, if they look clean & not melted any where I would suspect that it would be the ballast.if you got one of those pen type current indicators you could easily find where the power stops. If you have current up to ballast but not after it's you ballast, if power after ballast it could be a couple of your end caps. You might be able to take the fixture to a place like Eccol or Westburne to have it check out.