My ONLY, annual, customer.

No, not Marvin. 
Towards the end of the Shop's life things were reduced for sale. One bloke bought a Casio© Protrek. Ever since the shop closed he's come round to the Bungalow with it for a new battery. I tend to buy them next trip down town & he comes back "next week" to pick it up.
This time the crack was a bit better/longer and it transpired he was en route to Marvin's with his Gran's watch for S&OH, so I said ask Marvin for them. He did, then came in for a bit more crack while I changed the two batteries.
He returned a short time later ... his favourite button had gone on strike. Seems there's a Barometer function built in which he uses on "Washing day" to forecast whether it was wise for Mrs. to do the washing that day or wait.
Seems the old skill's still there, I got it "fettled" no problem.