Hi. I have ordered an Aguilar OBP-1 (on board pre-amp) to go into a Fender Jazz Bass. I will receive it in a week are so. The preamp comes supplied with two pots - bass & treble. They have a 'split knurled shaft with a brass sleeve' but Aguilar don't specify the lenght of the shafts. Would anyone know what size / type of knobs would fit these pots? I have e-mailed Aguilar with this question but as yet have not received a reply. Looking forward to hearing from you. Regards, Meanjd.