Good discussion there FTG & SBQ
If I could also add

Do your utmost to avoid legal routes. It destroys goodwill

If one was looking to buy into your situation. Q for yourself
Does the SH agreement stipulate revaluation of the business every year & its methodology?
If SHA has one what is the profit multiplier for its goodwill valuation?
How much of the profit is paid out as dividends?
What is the likelihood of private equity wanting to buy into/buy the company?
What is the likelihood of listed company wanting to buy into/buy the company?
Can the company buy out exiting partners shares?
Can the company guarantee SH loans to buy shares?
Does the bank have personal guarantees from shareholders?

How are you going to get a return on your investment?
Dividends or revaluation returns or a mixture of both?