My PVS 7 has recently developed a lot of tiny sparling dots. Don't really know how to describe it; hundreds of very tiny flashing (sparkling) dots popping and flashing; kinda like when you turn it on with cap on? Not seen this so pronounced before.

Is your manual gain up to high or are you in a darker location with less light than before? I'm not sure on how new you are to NV, so I'm starting with simple problems/fixes.

Might just be a little darker, little moonlight tonight, thin layer of fog rolling in. Don't think I have an adjustable gain.

Stolen from TNVC:
Scintillation: Also known as electronic noise. A faint, random, sparkling effect throughout the image area. Scintillation is a normal characteristic of plate image intensifiers and is more pronounced under low-light-level conditions.

Depending on your Gen/performance of tube the better it will preform under low-near dark conditions. Use of a IR illuminator will help in darker conditions.

Thanks this describes it. Scintillation is most likely it reading the description in a manual. Thanks.

Two things cause scintillation.

1) EBI - This causes very dull scintillation - Normally, unless it's really, really dark, you won't notice this.
2) Ion Strikes.

2) is the problem. It's caused by electrons colliding with gas molecules within the tube. When this is increasing, it means the tube is taking on more gas. That means the tube is dying.

How much longer? Who knows. If shading occurs, I'd say months to a year. For other gas problems, 2 to 3 years? If it gets worse when it's off, then I assume gain will decrease until it's not usable.

Check it on a really dark night next to a good one. Don't start worrying about a tube until you *know* it's faulty.

David. 

Thanks for advice guys. I have a 14 I can compare it too. The 7 was used so I have no idea about life on it. What would an average cost to have it repaired?

Lots of options for replacement tubes on epay.

+1... Easily solved. 

But as I said, and I should stress, until you know it's broken, it's not broken.  We all see different sides of our night vision gear depending on how dark it is. We're not very good at judging how dark it really is, so you might just have looked at it on a very dark night.