It is possible to straighten a bent leadscrew with a rubber mallett, a curved surface and some judicious and careful thumping and constant checking. Its a lot easier if the curvature is across the whole length, but Mike's looks like its at the end.

WHile I agree, Peter, there is little to lose, 12mm leadscrews being readily available, the issue is Mike has no machining capability (although there was a thread where someone successfully 'machined' a leadscrew end using some 12mmID bearing blocks, and electric drill and a file...). In an ideal world Mike would return these parts as 'not fit for purpose' and get relacement/refund as appropriate, but as he has said this is a problem...

Like you, Peter, I have bought stuff from MD without major problems, but I am increasingly hearing of people having more and more issues with them. It would seem that MD is overwhelmed by his success and is unable to provide an effective level of customer service.