This harp is a crochet action from ca. 1800 – 1825. It is not by Erard; there were a number of smaller makers producing crochet action harps well into the 19th century.
I’m afraid the harp is not in good condition. The soundboard has been replaced at some point, and the harp has been painted over. Quite a bit of the decorations have been broken off. The metal reinforcements on the neck are a strong indication that the neck is broken. It appears that when the reinforcements were put on the frets (against which the crochets pull the strings) were removed.
Please do let me know if you have any questions about this!