(Bloomberg) — Tesla Inc.’s Elon Musk told employees the electric-car maker is having issues boosting output of its new Model Y crossover and said he’ll be walking the assembly line on a weekly basis to troubleshoot production snafus.

“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 for new products,” Musk wrote in an internal email sent Saturday and seen by Bloomberg News.

Representatives for Tesla did not immediately respond to a request for comment. Business Insider reported on the email earlier.

Musk has predicted the Model Y will eventually surpass the Model 3 sedan as Tesla’s top-volume vehicle and could outsell all current cars in the lineup combined. Tesla shares rose 7.3% on Monday to close at $949.92, a record high.