Davey

Can see discussion of the TFA anemometer (and I believe a Honeywell model sold in the USA is similar). My problem is that I replaced my TFA anerometer unit under warranty in mid-2015, but now again I get very low wind-speeds recorded, maximum 11 kph, in what are very strong winds (in South London). The cups appear to spin freely, and I've recently replaced the batteries. Things otherwise work well. Does anyone know - is it possible to do a repair? Otherwise, I see reconditioned units on sale - would they be a reliable buy?