Just wanted to thank you for the details, I actually fixed the problem , I can't believe it. As mentioned above I had found spliced wires which were visible but with no conclusion to fixing the upshift mode. Many people steered me to buying a new gear assembly. I took your advice and unscrewed the cover on the right of the gearbox and to my surprise there were two wires which were completely cut (weird- no mechanical piece around it to do that damage). I re-wired and put it back together all works. Thank you very much for the write-up. I would suggest to anyone having this problem to first check the wires and not change the assembly (for those not under guarantee anylonger).