Cool little oldie autoharp , lisalee21 .
The big deal with instruments is to have them in good working (& clean) order ... they're designed to be so .
When it comes to autoharps , condition of the 'felts' that contact (or do not contact) the strings is important , as they do wear with use , sometimes to the point of just muting a string , rather than the silencing the string can occur . Older ones (felts) sometimes have been 'attacked' by moths , mildews &/or molds , so look for that too .
The potion of the instrument that contains the 'buttons' that are pressed (to 'auto-make') a chord can be removed for cleaning/adjustment/repairs (& also for installing a diff chord-felt & maybe finding the mod/pat #) as a unit .
Usually nobody but a musician or a lutier would know this ... it's not too hard to do if you are not too mechanically reclined .... there's a bunch of springs & posts that need to be properly aligned for a successful re-assembly , though .... the usual method for the older ones is to fully unscrew the fingerboard/feltbar assembly , turn the instrument up-side-down & gently lift the autoharp body up off of the f-board assembly .... but sometimes the method is reversed - keeping the fingerboard 'on top' for disassembly (when the instrument has a 'fixed' index for the chordbar assembly) .
These little guys have been (& still are) used in classrooms all over the country ... fundamentally an easy instrument to strike chords upon , though can be finger-picked into making great music ... all this in a portable (& relatively inexpensive) instrument a portable piano for po' folks !
It's tuned in octaves , and is much better sounding when it has been so !
With funky old strings , the instrument will not have as good of tone & projection , so I'd say (if it were mine & going to be played) it's way past time for a new set .... have not bought a set for many moons , as my 'boys' walked away with my former autoharp , but it seems like they used to run around $45 USD for a set .
The construction methods used during the building of such instruments is important , esp since the frame/body of these types of stringed instruments is under quite some stress . Spruce-topped autoharps are generally better quality than other "toppings" .
I'd give it a very close inspection , esp at any & all areas that have been glued together .... also look for any bowing of the top & bottom (not a good thing, but common in older units) .
I wouldn't go too wild with anticipation of it's value just yet though ... see if it's a good solid unit before investing in a new set of strings (esp since a new set of strings usually is just a great selling point & adds little to the value of the instrument - it just improves it's condition , which is supposed to be good , from the get-go .
I suggest getting an autoharp pitch-pipe at a local music store , tuning your harp (& play it some) .... let it set for awhile & then play it & see how it holds it's tune (sometimes people get rid of autoharps when one or more tuning pegs go 'south') .
Temp & humidity affect these stringed instruments , so please keep this in mind , when storing the unit ... damp enough humidity with a fully-string tentioned autoharp can & will permanently warp the woods , to bad effect .