Suggestions for fixing a fretboard

Hello again!

I ran into several problems while making the fretboard for my dulcimer:  

1) I had some trouble fretting it. The fret saw I ordered from folkcraft was supposed to be the right size for the fretwire they gave me but for some reason I couldn't get the frets to fit into the slots. I tried to widen the slots with another saw but then they were too big. Would it work to either glue them in with super glue, or fill the slots with wood filler and try to cut the slots again? 

2) A few of the fret slots also turned out a bit crooked. Not sure if there is any solutions to fix this at this point? I just read online that cutting the sots while using a square helps avoid this problem. 

3) The headstock of my dulcimer is also part of the fretboard (rather than a part of the endblock). I basically just cut an oval-shaped slot/hole in one end of the fretboard, but I made the sides of the slot too thin for the screws that came with my tuning machines. 

Given all the difficulties I'm having with this fretboard I wasn't sure if it makes more sense to try and salvage this one or just to try and make a new one? The other idea I had was to fill the fret slots with wood filler and then glue a thin piece of wood on-top of the fretboard so that I can re-slot it (although that wouldn't solve the headstock problem). Any thoughts or advice any of you have on this would be greatly appreciated. 

Sorry for the long post!

All the best, 

Haley