Thanks so much to all of you for your input and suggestions. I brought the lens to two local repair shops here in London (Aperture UK and Sendean Cameras). Both confirmed that the lens can be fixed and one quote was actually very reasonable with around 70 GBP. However, I decided to not sink any more money into the lens and send it back to the seller in Japan. Got the money back from the seller and now I have to deal with Her Majesty's Customs and Revenue Service to get the VAT and customs duty back - joy!
Shame that the seller did not describe the lens accurately and this was the first time ever I have been let down by a seller from Japan who are usually very honest and great to deal with. Anyway, got my money back and invested most of it into a very nice Voigtlander 35mm f2.5 Color Skopar Classic.