Looking after your Tromba's Valves
The valve block sleeves are made from brass and whilst the core of the valve is made from ABS plastic the valve outer is made from stainless steel. So unlike some other plastic instruments on the market the contact surfaces of the valve are metal like a conventional brass instrument ie stainless and brass ! Thus you will need to use valve oil. I recommend Blue Juice as after several years my Tromba Trumpet valves still work great and the plastics do not show any signs of degregation.
One final thing. If you have a rubber washer inserted in the upper valve cap then please do not squirt valve oil over the washer and stem intending it to drip down to the valve surfaces. Apart from being a waste of oil as very little gets to the friction surfaces, the oil eats in to the washers causing them to warp. The best way to lubricate any instrument valve is to lift the valve out and gently squirt oil over the friction surface before re-inserting and rotating to spread the oil.
Don't forget to make sure the location lugs are aligned. Valves 1 and 2 the large lugs are on the right and Valve 3, the left (as you're holding the instrument)