Hi,
today I was crawling through some old bunkers and shafts and due to my clumsiness I was partially covered in sand.
The problem is that my HV20 got sand behind the lens doors.

It now is jittering and struggling to close or open the lens doors, and is able to do it only partially if unassisted.

I tried blowing really hard, but it didn't help much. I don't have a working warranty for the camera any more because I bought it some time ago in the USA and I'm an ocean away and don't have the receipt.

I'll try to buy some compressed air next week to try to blow it out, but I think it won't do much good.

Do you have any suggestions? Can I somehow remove the front part of the camera in front of the lens to clean out the sand from the lens doors?
If the compressed air won't help, I'm thinking of switching it on/off so many times that the sand is grinded to dust, but I'm afraid it can do damage.

sand is harder than plastic... so the more you force the issue, the more damage you're likely to do.

Compressed air may do better than you think, if used with care, or perhaps one of those small keyboard vacuums with a concentrator nozzle. If the sand isn't too sticky, you can probably carefully blow or suck it out of the mechanisms if you're patient and work in a clean environment.

Taking the camera apart is probably a job best left to a qualified tech, unless you're comfortable with lots of small screws and such... but may become necessary - this is the downside to "built in" lens covers.

If you're going to be in difficult environments, you need to protect your gear, or plan on replacing it a lot sooner that you'd like. I would expect if you got sand in the lens, the odds are good that there's grit in the tape mech and other nooks and crannies, may be time to pay for a pro cleaning? Typically sand, water, etc. and delicate electronics and mechanisms are not a good mix... precautions are warranted.

Thanks for your advice, Dave! Will try to clean it with compressed air before trying anything else.

I think I need a camera in a rubber coating...
We were counting a bat population, and then a cam is really handy, because it can see in angles and places humans can't, but it also means getting it in really nasty places too...