I can't offer a Yashinon-specific recommendation, but I can recommend two repairers I've dealt with recently. Newton Ellis in Liverpool (advertises in AP) repaired my Yashica Y72E half-frame camera (wobbly lens mount, frame counter broken, erratic selenium meter), and did a fine job on it. My Contax 167MT was repaired by Protech Photographic, and likewise they did a fine job, at a reasonable price. Both of them gave me an estimate based on a telephone diagnosis, and both repairs came under budget. It's worth giving either of these a call.