A thought occurred to me: if the major “issue” here is that it does not hold tune well, that may be because the peg holes have become too smooth. The remedy is easy:
Take a look at the more serious culprits and if that’s the case, rough up the peg with 50 grit sand paper and ream the holes lightly either with the same sand paper gauge or a tapered reamer – probably a #4, possibly #5.
Alternatively, if the strings are pretty old it is possible that the “knots” are worn and kinked. If you can fix it that would sure beat buying a brand new harp!
A reamer is a good thing to have on hand anyway for a dedicated wire player.