I hate those modules. I hate them so very, very much. Why Hamilton went from Time Computer modules (their own division I might add) to Frontier, is beyond me. I guess they had to "dumb down" their 2nd gen watches to make Pulsar's sell better.
Anyway, the quartz crystal is LIKELY the problem and needs replacing, but with Frontiers, there can be other problems, some of which can't be fixed (which is mostly the case) and some very simple like the batteries getting poor contact or the battery contacts on the module needing to be cleaned. I wouldn't suggest the later for most modules since it's getting power and probably doesn't need to be cleaned, but Frontiers are Frontiers. Did I mention I hate them?
Jeff