Compound Ammonia Screw Compressor controls made by ASEA / STAL...can't find parts or service any more. QMAT-503, QAL8-111, QAPS-110, QALP-210, etc. (Monitors inputs and operates capacity slide valves, etc) What systems come "recommended" as replacements for these old controls? Brands, types, part #s, websites. Any info would be appreciated! Thanks!!