On my B2301, have notice the last couple times mowing the tachometer needle seems to be what I would call 'fluttering'. Engine rpms sound constant and runs fine/normal, just the needle on the dash bounces ever so slightly (maybe 1/16th of an inch) around the 540 RPM mark. I don't remember it doing this before... always seemed to keep dead steady....but then maybe I just never noticed. Wondering if I should be poking around for a loose cable or wire?