They used Aluminum engines, which were over-engineered, and prone to failure. Also, slave laborers have a tendency to commit sabotage.
Initially, the Maybach HL 210 aluminum engine was used but was quickly replaced by the cast iron, Maybach HL230. Reducing the weight of the Panther would have further reduced engine/transmission strain.
which were over-engineered, and prone to failure.
Not rushing to production could have eliminated many of the bugs.
Also, slave laborers have a tendency to commit sabotage
In addition to the effect of low morale on product quality. The overall (poor) quality of product produced by slave labor is a problem the German High Command with it's obession on absolute production numbers never seemed to recognize.