Deep/Normal switch- how config'd?

Im wondering about this function on my 130 (which seems to make no diiference when switched between). The switch itself is fine, checked; so is the 'normal' setting mean the OD capacitor is engaged, or vice versa?
If normal= cap engaged perhaps then I can diagnose the OD needs replacing (as a 1st try n fix). If deep= cap engaged then Im stumped / any ideas on why it no work helpful. thanks rc