Our boat came with Faria gauges. The tachs are "rebuildable" when they go bad, but engine hours (if included in that model tach) get reset to zero. Maybe their other gauges are rebuildable, too.
The analog tachs were also calibrate-able. Sort of. At one RPM level... and then not all that accurate at opposite ends.
I went through that goat-rope on both tachs, then finally replaced them with Aetna digital tachs... and once the fual gauges started acting up I replaced all the other gauges with CruzPro digital gauges. (Aetna's tach fit the existing 4" hole, otherwise the CruzPro tach would likely have been fine too.)
South River, Chesapeake Bay