1. Was there any difference in the blast hose?
2. Is it the same material, same thickness, same supplier, same length of hose, same type of fittings?
3. Did the intensity change right after you changed the blast hose? If the new blast hose inside diameter is larger it will have less pressure drop towards the nozzle and this will give higher velocity and therefore higher intensity.
4. What about the Almen strips? Are they the same supplier and same lot number?
5. I presently suspect the blast hose as the problem but there could be another cause. What is the size of the blast hose (inside diameter) and what is size of blast nozzle?
6. What is your air pressure setting?