Unable to get DoCmd.OpenForm "frmInstrumentServiceRecords" to work.

I have a form frmInstruments that lists a number of different instruments in the table tblInstruments. Located on frmInstruments is a command button btnAddEditMaintenanceHistory that when clicked I would like it to open frmInstrumentServiceRecords only for the the instrument currently displayed in frmInstruments.  Seemed easy enough but after two days I am stumped.  Below is the code for the click event for btnAddEditMaintenanceHistory.

Private Sub btnAddEditMaintenanceHistory_Click()
     Dim vInstrumentServiced As String
     Dim vSQL As String        
     vInstrumentServiced = Me.InstModel
     vSQL = "[ServInstModel] = " & vInstrumentServiced
     DoCmd.OpenForm "frmInstrumentServiceRecords", , , vSQL
End Sub

Me.InstModel is the Instrument field name on frmInstruments.  ServInstModel is the field name on frmInstrumentServiceRecords that needs to be = to Me.InstModel.

When I run this I get a runtime error 3075 "Syntax error (missing operator) in query expression 'ServInstModel = Ampico B Mason & Hamlin 5'8" Grand.

Any thoughts?