Decoding the Right Wing's Social Security "Facts"

In the video above (edited by Think Progress here), Ron Johnson, R-WI, claims that the Social Security Trust Fund (the fund that accepts payroll tax contributions, loans the money back to the government for interest and pays benefit to Social Security recipients) is a "myth" because "the government is essentially writing itself a check." Economist Paul Krugman points out that if  Rep. Johnson's assertion was right then the entire Federal Budget is a myth and that "your facts are false". What's going on here?

I actually think everyone understands the facts of how Social Security works (I'm being generous to Rep. Johnson because he's from my home state). What Rep. Johnson is saying is that the Right Wing has no intention of paying the Social Security Administration back the money it has loaned the Federal government. He is right on this "fact". Ever since the Social Security Administration was formed in 1935 by the New Deal, the Right Wing has vowed to destroy it. Refusing to pay the funds back or using a crisis (such as the Subprime Mortgage Crisis created by Right Wing Bush II Administration policies) to argue that the government is broke and cannot pay Social Security back, all of this would be a great way to destroy Social Security.

Think Progress ends their piece with the following factual statement:

The Social Security trust fund is solvent through 2038, and the program would almost certainly have long-term solvency were it not for the Republican-backed cap on payroll taxes for income above a certain level.