Did you by any chance change resin brands at the same time you purchased the new equipment? Everything you describe is more consistant with a resin problem rather than what tooling is being used. In regards to your last question about the "new" cracks that show up later: If you are using proper procedure and not applying heat indescriminately, the curing process will almost always reduce the amount of rays you can see in the finished repair. However, the amount of 'sparkle' in a finished repair is directly related to the viscosity (thickness) of the resin. The thinner the resin, the more sparkle. Why? Because there is a greater difference between the refractive indices of the glass and resin.

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