Googling myself this morning, after my four mile walk, I came upon a very long and very interesting discussion taking off from my exposition of Ricardo's theory of rent, written by the person who often comments on this blog under the name "Marinus." The link is here:
It would take me a very long time to react to the complex discussion he [?] develops, but I recommend it to you. One quick response: Marx's discussion assumes one class or quality of labor [roughly speaking, semi-skilled labor] and a "reserve army of the unemployed" always available to compete for any job, thereby driving the wage down to subsistence. But in fact, as I have argued in my essay "The Future of Socialism," that is not how the labor market developed in the years after Marx wrote.
My own effort to re-analyse the situation can be found in my essay "A Critique and Re-interpretation of the Mabor Theory of Value."
At any rate, I want to thank Marinus for the extremely suggestive and interesting analysis.