The problem is manifold.
Yes, the pendant itself is too light in comparison to the rest of
Because its a fine chain it has no roll resistance, that is there’s
nothing to prevent twist in the first place.
The JR at the junction of the chain to pendant is too small, so that
once twist happens, the JRs bind and lock in misalignment.
IMHO the value of the piece doesn’t warrant trying to fix it. Sorry.
Its simple cost/benefit. About the only thing that would be
inexpensive is to ‘glue’(yuk) some heavyish metal to the back of the
pendant. And that addresses just one issue, so it may not be enough.
Don’t heat this piece, short road to heartache.