Here are a couple harps I've been working on...
I opened up the back covers sealed them with cloth tape.
Here I am waxing the draw reeds. This helps a ton with overdraws which I am doing more and more of. The reeds have been embossed, arced, and gapped to my needs. This is always tricky because the reeds will drift back to their original shape and gap from time to time. So I tweak, play, wait a day, and resume. Throughout the week I'll come back and tinker to get the best overall response and feel.
Here is the comb after I sealed it. Note that I removed the plastic burrs that run through the channels. The harps will be played a bit daily for the next week so I can work out any kinks. The last thing I do is tune the harp to 443, but the reed work and wax can play with the tuning. I guess I have to be patient!
Typically, I play Golden Melody harps. However, they aren't made in the low keys. With the GM's, I typically don't mess with the comb. It isn't as easy to cut as on the Sp20's. However, I have a Dremel tool I just bought. I am now starting a GM in Ab that will be cut and taped. My preference is for wood or composite combs, however. I have three coming this week from Chris Michalek of Buddha harps. They are worth every penny! That being said, the Ab isn't on the list of comb priority, lol. Those will go in a C, D, and Bb I finished this month.