How to prevent Meringue from turning chewy/gummy-like? My attempts at Meringue-making are driving me a tiny but crazy...

No matter what I do, at first, they are still wet on the inside, and if I leave them standing longer to dry out, they get a chewy/gummy-like consistency when bitten into (this is really the best way I can explain it).

I am currently working with 50-60 grams of granulated sugar per eggwhite (depending on what size of egg I have), a slightly heaped teaspoon (not the measuring-kind, just a regular, european teaspoon) of cornstarch per eggwhite.
I add a pinch of salt to my eggwhites before whipping them up, then slowly add the sugar. Temperature-variation of the eggwhites did not seem to do much about the chewiness-Problem.
I have tried drying between 70 and 100 decrees Celsius (most recipes seem to call for 80).

How do I get them to dry all the way through without burning them? I SUSPECT the fact that I seem unable to get them all dried out is the actual problem!

EDIT: For size: I usually strongly heap a teaspoon (mostly because the whole issue with a piping bag seems futile to me if the texture does strange things anyway...). They are not overly large, I'd say, and I even have the chewyness-issue when I make very very flat ones.
I'm pretty sure the problem is in using too much starch. Try less, or even learn to whip meringue which does not weep - you need to get both the speed and whipping time just right - and then skip the starch altogether. You can also try making Italian meringue, it's much easier. It also doesn't need starch. 

Also don't use salt, it interferes with foam formation. Use a pinch of acid for more stable foam, but don't overdo it.