hi just bought a radio for my caravan. all web sites say serial no is on the side well mine has no number etched to it all. i have 22dc752/79R. and wao3724L1 then 677977 the only other thing is a bar code sticker with 61699304 on it. thete is a small post it note type sticker with 48371 whick i suspect is a jom number for a poss repair? any help would be good