Good tremolo player named Norm has a Facebook page about his tremolo harps and his playing. It's a private page so you have to message him to join. He recently posted some nice photos of a home made 7 harp paddle wheel using Echo Celestes.
He gave me permission to share the link here, so shoot him a message if you would like to see those pics and hear some good tremolo playing. https://www.facebook.com/groups/247325412308734/
Recently saw this case at a Gander Mountain store. It was near the fishing tackle boxes. It will fit the longer 24 hole harps side by side. It is a Flambeau T6004. The one I got was a 6004R which is the same case but it has movable blue plastic dividers that have some type of rust proofing chemical on them. I didn't realize that until I got it home. Their web site says the chemical is safe but I don't want any chemicals near my harps so I have made my own dividers by cutting some old insurance cards and using some diagonal dividers from another, smaller case I already had. The round thing is the spool left over from a roll of tape. The T6004 comes with plain plastic dividers so that would be the better one to get. You can order the plain dividers by contacting Flambeau, but the shipping cost more than I paid for this entire case ($8). 24 hole harps will fit side by side with the spool dividing them. Dividers can be spaced closer to fit 21 hole harps. I have a 21 hole in the bottom of the picture but the divider there could be removed and a 24 will fit there also. In the upper right is another 21 but that divider could be removed and a 24 would fit with just the spool between them. The 21 hole harps have tapered covers which means you can face them opposite directions and fit two per slot. I used to do this with my old case and wrap the harps in their cleaning clothes so the covers didn't rub and scratch each other. I put a little double ended screwdriver in one of the small spaces and a Seydel Big Six in the other. I retuned that Big Six to Melody Maker. It can play a surprising number of tunes.
Here is a video I made today that explains what to adjust to fine tune the tremolo speed on different notes of your harmonica. I did not demonstrate actual tuning because there are many videos that already do that. Instead I put links to some of those in the text below the video so you will have to watch it on youtube to see those. The tuning videos on youtube show how to tune diatonics and chromatics but they never explain what to do with a dual reed harp. Hopefully this simple explanation will fill in that gap.
Learning and playing the tremolo harmonica has opened up so much new music to me, like Irish tunes, a re-aquaintance with traditional Appalachian folk music, and now French Canadian folk (see the links below).
These tools allow me to tune a tremolo harmonica without constantly removing and replacing the reedplates on the comb. This saves a tremendous amount of time and frustration. The "5 cent tool" has a "tail" on it for supporting inside reeds so you can tune them from the outside (with the reed through the slot) but it won't work on any of my tremolo harps, the blow reed tips are near the holes which is opposite of a standard diatonic. However, the straight end of the brass tool works great to push the reed through the slot and then I use the "plinker" in the kit to support the reed while it is tuned. There are two scraper type tuners, one on the 5 cent tool and one on the wrench, which work for making fine adjustments but they are not best if the tuning is way off or if you are wanting to tune a reed to a different note. A file or a Dremel tool are better for that. I have both a small file and a Dremel so I have all the tools I need now.
I have found that even though you can tune with the reed plates on and the covers off you really have to put the covers back on for the final test. Things can change after the covers go back on and then you have to start tweaking the tuning ever so slightly and putting the covers on again to test. This will show up mostly in the tremolo rate of the note.
I am using this tuner: https://www.seventhstring.com/tuner/tuner.html It will run in Internet Explorer but not Google Chrome. I downloaded it (instructions on the web page) and run it offline. I also take my computer offline when tuning so only the tuner is running. I place my computer mic a little bit away from the computer so it doesn't hear the fans humming and I also fold up a wash cloth and set the mic base on that to insulate it from vibrations coming through the table. I have had good success so far with these tools. I am going to post a new review of the Easttop tremolo since tuning it.