Due to a diff problem (broken tooth) had the diff and while at it the transmission rebuilt last year.
Since then there has been a humming noise from the transmission in 4th gear only, more pronuonced while cruising (no load).
Any inkling as to what the source can be? Many thanks.
Thanks Sportiva. When I'll get a chance I'll have it diagnosed by the the workshop that did the repair / reconditioning of the transaxle.