Hi there, I have an Alvin Keech Banjulele that I have had for 45 years. The serial number is R1810 supplied by Leanord Dews, Blackpool. I do not know much about it and im just wondering if anyone can give me an idea about to how much it is worth and from what year it is? It is in pretty good condition but the box is tatty. Any advice and replies would be very grateful. Thank you!