Nope, I stand corrected. I checked the procedure in the manual and you have to drop the valve stem below the level of the stem seal, usually done by removing the valve (after first removing the camshaft, valve tappet and spring). If someone knows a way of dropping the valve down enough to replace the seal in the guide, and then raising the valve to reinstall the spring and tappet, then that would work. Maybe by stuffing the cylinder with rope or something through the plug hole, you could keep the valve from dropping, and use compressed air to push it back up. Just a thought.

But the good news is that removing the head is not that big a deal. One grand is still too much for this job: you need to find another mechanic. The B230 head is simple, access is easy, and to pull it off should not take more than about 90 minutes for someone who is experienced and has tools.