I just started hoving inverted, to hold inverted flight, I'm having to hold a lot of up elevator. Is this a center of gravity problem??
Thanks

What kind of helicopter is it? Something you want to keep in mind is wind. I like to center mine on a very calm day. If the wind is blowing to your right, the heli is going to want to roll that way. Same if the wind is blowing in your face, the heli is going to want to roll, flip towards you. And it doesnt take much. You may think it is off center, but really its not.
Now thats not to say that your heli isn't off center. A good way to check is have the blades straight out from front to back (i always take my blades off so there is no mistakes) with the paddles going left to right. Grab the heli by the flybar with your fingers as close to the head as you can without touching the seesaw or head. Pick it up and the heli should stay level.

I think you figured it out. Maybe you're having to hold down-elevator (or down trim) when rightside up? If so, perhaps it's tail heavy, and when inverted that would require enough up elevator to to cancel the down trim plus that much more to compensate for CG. It sounds like a CG problem to me. Straddle the heli with the blades in the fore/aft direction and hook a finger under the flybar on both sides, as near the hub as you can get, and lift it off the floor and see if it's tail heavy... the skids should be near parallel to the floor if it's balanced. The only thing I can think of to do about it if it's tail heavy is to replace the battery with a heavier (more mAh) battery.... or add a brick up front.

Needless to say, if it's tail heavy rightside up it's gonna be tail heavy upside down; it's just that the elevator control usage is reversed when inverted.

It's an Airskipper 50.
I checked the CG, it appears to be slightly tail heavy, I really don't want to add any more weight up front. Are there any other options.
Thanks

Make sure the battery is as far forward as you can get it. That's the "big gun" as far as weight goes.

You might get a chunk of lead, maybe tire weights, add to the front to see how much weight it takes to get balance. It might not take a lot.

If there's room in the canopy you might be able to extend the nose a bit... bolt on an aluminum or wood plate to extend the nose and then move the battery farther forward by setting it on that plate.

Being slightly tail heavy with no fuel, it will be a bit more tail heavy with fuel.

There is little to do at the tail to lighten it. Can't very well shorten the tail tube. Guess I'm out of ideas.

Yep, move the battery or use some stick on lead, proper balance is key to trimming upright and inverted.