I’ve a test routine when I try harps (lever or pedal harps) for myself or students.
But Maybe you have a different way?and new ideas?
1) I check the appearance of the harp: are there cracks, impacts, etc, how is the harmony table, the column, etc
2) tune and try the mechanics: are they in tune?easy to move?or hard?noisy?are there some buzz?
if is something wrong, is that something I can check by myself?
3) I play different things: slow arpeggios and hear is the sounds is equal, feel the tension of the strings, chords and hear the sustain, play loudly or soflty to see if the harp is responsive, try as much techniques as possible to see if I feel at ease.
Is the harp confortable for me?
4) subjective feeling, what does the harp say to me when I play it? 🙂