Want to share with you the results of re-building the broken sprocket cover holder on left side crank case of my DT 250B motor. A friend of a friend has access to a Laser welder. I prepared the case with a file and machined an Aluminium bushing to be welded on. As well a steel holder, to hold it on right place, where the hole belongs. Had no idea about laser welding before and trusted him... Must say the result is amazing. The welding is perfect, as it is. On the pictures, it´s not machined over. Surrounding area didn´t get hot, so beatings and caps stayed in place without damage.
If you had to weld similar, look for a company with laser welder

Boy thats cool stuff, I remember your thread on the hard soldering for the Thermal Flow shocks.

Tell me where you live, I'm retired, I can be your assistant.
I considering taking a welding class at the local Jr College.