Not 100% but it could be as simple as your volume control pot has some corrosion- more so if stored as you said. Not too hard to remove and clean up. CRC have a few good products to assist. Pretty sure they are available at Jcar. If you are not confident and in Sydney PM me and I can give You a contact for a great tech
In the last 2 games our halves have been receiving quick clean ball from DH and as a result Brooks and Marshall have probably played their best games of the season. And points have flowed according Farah has not been able to provide that. Grub has also provided energy and spark. Would anyone really consider changing this simply to play someone who would more than likely breakdown in the first 10.