Things are reportedly not going smoothly with the restart of Tesla’s main factory in California.

Last month, CEO Elon Musk threatened to move Tesla operations out of California and sued to force Alameda County to allow Tesla’s plant in Fremont, California, to reopen. Musk is an outspoken critic of stay-at-home orders, which he called “fascist” in a profanity-laced call with analysts in April. He also is a skeptic about the threat posed by the pandemic.

The Washington Post has reported that at least two employees of the Fremont complex have tested positive for Covid-19 since it resumed operations. The Post cited unidentified employees at the plant who were briefed by the their managers.

Tesla did not respond to queries about the report.

The Post story said that while the employees who tested positive have not returned to work, co-workers who were exposed to them are back at their jobs after a 14-day quarantine at home. It did not report any disruption in production caused by the employees testing positive.

Most automakers suspended operations in March and resumed production in May. Many, including General Motors, Ford, Fiat Chrysler and Volkswagen, have reported at least some of their employees at US factories have tested positive for Covid-19 since work has resumed. Other automakers have mostly continued production even when employees tested positive.

But Covid isn’t the only issue Tesla is facing since it resumed production.

In an email Musk sent to Tesla employees, reported by electric vehicle news site Electrek, the CEO said that there have been problems ramping up production of the Model Y, the lower-priced SUV that Tesla started building earlier this year before the shutdowns.

The Model Y is a key vehicle for Tesla and is expected to become its best-selling vehicle. In April Musk bragged to investors that for the first time that Tesla had turned a profit on a new vehicle in its first quarter of production.

But the email said there were problems with Model Y coming off the assembly line that required significant repairs, a process known as rectification.

“It is extremely important for us to ramp up Model Y production and minimize rectification needs. I want you to know that it really makes a difference to Tesla right now,” he wrote.

He also said that Tesla had experienced problems with the supply chain for the Model Y. The email did not provide any details about the problems, but some automakers have experienced problems with suppliers not being able to ramp up production because of their own Covid-19 problems.

Musk said the company’s other three models, the Model S, the Model X and the Model 3, have not experienced the same problems.

“We are doing reasonably well with S, X, and 3, but there are production and supply chain ramp challenges with Model Y, as is always the case with new products,” he said.

Musk vowed it would take a hands on approach to deal with the problems. “Will get better fast,” he wrote. “I will be walking the line personally every week.”