overbored77,
It's not really too hard to do with covering.

1. Use tape to fully deflect the surface you want to seal the gap for.
2. Cut a strip of covering long enough to cover the entire hinge line (if possible). Fold the strip in half and set in the gap.
3. Use a trim iron (or the tip of a covering iron) to iron down one side of the strip against the "V" of the gap. Make sure the fold of the strip sits all the way down in the gap
4. Now do the other side of the gap with the trim iron.
5. Now use the covering iron to seal down the rest of the strip onto the control surfaces.
6. Trim the ends of the strip.
7. Now flex the surface and then inspect the gap. If there are any parts of the strip that came up use your trim iron to seal it back down.

Do both sides of the gap this way. Doing this will reinforce the CA hinges to help prevent failure.

Hope this helps

Ken