I'd written a post on selecting "real" pocket pistols awhile back.
It describes what to be looking for and what will be the better shooter.
One of the very first and best things that you can do to one is to clean it thoroughly and then see how it indexes.
In many cases - the build-up of grit, oil and powder fouling is profound and a good cleaning will work wonders with timing, extraction and ignition.
Spare parts for these little guns are inside the guns of other people, so replacement parts can be a problem, though Gunpartsco and Dixie have some odd things - as do other suppliers.
If you're going to get involved in doing your own repair - remember that slave pins are going to become your friend, and proceed slowly.
Good Luck.
Scouts Out!