Problem: Bargain lens [Sigma 135mm f2.8-64mm "Pantel" in OM mount] has one of its little levers [there are two on the outside of the lens barrel] for lens mounting non-functional — no spring action [lever just flops around in the slot] and I am loath to mount it on my OM-m43 adaptor to test out the rest of its functioning. I have a 3x Vivitar tele-extender in OM mount which I am prepared to sacrifice for parts if a repair is relatively easy for my friendly local lens mechanic/techie. I can only see him on Monday. Just wonder if anyone else has had similar problems and what the prognosis is. Thanks in anticipation.