(Dec 9): While Elon Musk is busy overhauling newly acquired Twitter Inc., Tesla Inc. is facing increasingly urgent issues and testing the faith of some of its chief executive’s biggest fans.

Weakening demand in China is forcing the electric-vehicle maker to slow production and delay hiring at its Shanghai factory. Its top executive for that market has been called in to help out at its newest plant, in Texas, which isn’t ramping up as planned. And Tesla’s stock, which has lost more than $500 billion in market value this year, is under renewed pressure as Musk’s advisers weigh using the billionaire’s shares as collateral for new loans to replace Twitter debt.