I had a Saturn water key put on the "dogleg" going into the horizontal main tuning slide on BART to replace the original style main water key. To me, I believe it slightly helped the low 4th valve G that can tend to be just a little fuzzy on larger CC tubas.LJV wrote: This is also my reservation on trying the Saturn water key. The plastic ring component seems to be a weak spot that can't easily be fabricated in the event of failure and lack replacement part supplies.
However, I did find out that the plastic ring can melt!
I replaced the tuning slide, and when I soldered the new outer slide onto the dogleg, enough heat was transferred to deform the tips of the ring that displace the ball, so that it would no longer let any water out when pushed. My fault for not disassembling the saturn water key before doing major work on the horn. I called HornGuys, and ordered a new ring along with two more saturn keys that I will eventually put on my 3rd and 4th crooks.
The designer of the saturn key said that is the first time he heard of the plastic melting.