A group of Tesla investors is urging Elon Musk to commit at least 40 hours a week to running the electric vehicle company, arguing his undivided attention is needed to repair Tesla’s faltering sales and stock price volatility.

In a letter, some skeptical backers of the EV company have also asked its board to add a “new, truly independent” member and lay out a succession plan.

On Tuesday, the company published SEC filings proposing the sale of securities under trading plans by members of the board of directors estimated to be worth nearly $200 million.