I have a new HSB Phiffi 0-6-0T and one of the wheel contact carbon brushes is showing as failed. There are no component diagrams or maintenance instructions for this loco (or the Mallets) that I can find. I've done this type of maintenance on LGB locos, but the underside looks quite different on this loco. I've attached a picture. Before I pile in and start unscrewing the base of the gearbox I thought I'd enquire if anyone here has experience of accessing the gearbox on these locos to change carbon brushes that could give me some guidance for this job? Thanks for any help.