Norman,
Did you just replace the headstock belt, or did you do the motor one as well?
I’d thought a lot of the noise on my S7 was coming from the layshaft needle rollers (which had previously been greased, rather than oiled) and was “getting around to” replacing them – hence my query.
Sounds (no pun intended) like it might be worth my changing the belt first and seeing whether that brings the noise level down somewhat.
Regards Tom