Why not just clean the menthol ones out?
Just use a pair of tweezers to pull the filler material out. Rinse the filler material out while holding the end of it with the tweezers. Be careful not to not mangle the filler material too badly while rinsing it. Blot the filler material dry with a paper towel. Let dry. Once it does dry reinsert into the cartridge. The tweezers will really help here. Without tweezers it is difficult to avoid jamming the filler material into the cartridge and wadding it up. A couple of practice tries and you'll be a pro. Try to get the end of the filler even with the end of the cartridge.
Also rinse the cartridge itself out with some water before you put the filler back in. Menthol is persistent, so I'd really rinse it well. When you're done rinsing, blow through the mouthpiece end to expel as much of the residual water as you can. If you can wait for the cartridge to dry overnight - great, if not - no big deal.
Once you're dried out and have reinserted the filler material (tweezers - hint, hint) then add a few drops of the juice slowly until it starts to pool on the top of the filler material. Stop and then assemble the cartridge to the atomizer, screw those two into the battery and give her a go. There are some very effective tips for refilling/optimizing cartridges, but those will come later.
Since menthol is so strong, you may detect a faint hint of it. But you have to break in the unit and the menthol will quickly fade.
These e-cig gizmos seem foreign when you first get them but after a little experimentation they're not complicated. It's just so confusing with so many mom-and-pop outlets selling them it gets really confusing with all the conflicting and incomplete information.
Congrats on choosing cignot for a vendor. They have done me right.