I know this situation is extremely frustrating. However,
If you've ever been involved in the sale/purchase of a business, you would know it takes time for both parties to go through EVERYTHING (Due Diligence) and both parties are typically bound by Confidentiality. I can't answer whether that includes not taking your calls, but everyone knows Mark has serious health issues, which stress is known to add to
As a thought, since you have waited this long, why not give it a couple weeks before seeking legal action
Having owned Furman, PS Audio Premier Power Plant and 3 CTPs, I know how viable the product is. Someone is/will take advantage of buying the company, and all that we've gone through will be a distant bad dream