Have you considered licensing your product to an up-and-coming China test equipment OEM? Or even selling your company to them? Or any other test equipment that can offer a higher value, or offer the best package. As a single product maker, after a long detour, with dilution through additional parties, your past decades of hardwork may still end up as a part number of a larger test equipment maker. You might as well get the best deal for all your effort and investment now. Of course, you are going in to negoitiate with a stronger hand after tempting a few investors to put their cash on the table, or liquidate youself in other means.
Which OEM need your product, and you, the most? This is the question I would be asking if I do not want to bother in doing business, and just want to a hired hand (CTO or not, may not be up to you).