Tuba still has valve problems. Need help.

[Dan Schultz]

If you remove your linkage, do your rotors spin freely? Is there a chance you are using too heavy or too much oil on your rotors? There is no way to diagnose the problem over the internet. Take your horn to a qualified technician.

[Dan Schultz]

You should know that the rotors themselves do not touch the cylinders.

Yea.... but the film of oil that seals the rotor gap DOES!... along with whatever gunk gets washed down the lead pipe. Closely fit rotors + heavy rotor oil + a little bit of sauerkraut can cause big problems with rotors.

All that being said, I own three rotory horns... a Miraphone 183-4 (Eb), a Miraphone 184-4 (CC), and a B & S stencil BBb.... and NONE of them have a single problem with sticking or sluggish rotors. Why?? ... because I keep 'em clean and oil the rotors very sparingly.... just a drop or two of heavy oil on the spindles and the linkage once a month or so. Heavy oil down the leadpipe is a mistake.

If you are certain your Amati is CLEAN and the rotors are still causing problems, you should take it back where you got it (assuming you bought it new AND from a reputable dealer).