Are the company's problems fixable?The problems that have plagued Plug Power (PLUG -1.01%) persisted in its second quarter as the company once again posted poor results. The stock has lost about 80% of its value in the past year.Let's take a closer look at the issues the company is facing and whether it has an opportunity to stage a turnaround.Plug Power's problemsThe biggest issues facing Plug Power are negative gross margins and cash outflows. The company found a niche selling fuel cells used in forklifts ...