As business owners, installers and just plain jacks of all trades we like to think that we have the requisite skills to overcome just about any obstacle. The "case of the plugged pipe" has been presented and solutions provided.
Let me offer this:
Are you getting paid to clear the pipe even if not successful?
Does the customer have an electrical contractor on staff or contract for just such an event?
Is installing new pipe an option?
Is installing direct bury an option?
What's the best course of action and you still make money?