[Rainer]

Probably the best you can do is to sell it with a detailed description of the error.



Working copies of this quite old lens sell around 150e - 200e on e*ay ...

for a partly defective one you might still get about 100e.



The failure could be a partly broken cable inside the lens ... in that case I

would expect the error to occur at certain focal lengths more often.



It could also be a dying aperture-mechanism.



In both cases, the error is hard to repair yourself ... and (since the lens

is quite old) I doubt there are still spare parts available from Tamron.



Just my thoughts ... Rainer