When I bought a new AK900 a mos ago, I bought a YJ Titan from Amazon. The valves are much improved from the earlier Titan, they close tight and open easily... well at least for the first mos they do... And the knobs are a lot larger, easier to use.
May have to replace the valve cores in my old Titan and put the new knobs on it. However the cost may be such that a new Titan might be reasonable. The old one is under a DC 1200/1250.