What internal political pressures did the Soviet Union experience in the 1970s and early 1980s?
This is a great question. By 1980 the Soviet Union had a massive army and their military technology was powerful as well. In fact, they were the only other super power in the world along with the United States. So, there was no military crisis, but on account of their military build up there were internal problems. Let me explain the rationale.
Because the Soviet Union spent most of their money on the military, they did not build up a strong economy. All their resources went into the martial side of the country. This caused and standstill in their economy, which resulted in a general population that was struggling economically and socially. This was compounded, because they heard about the success of their rivals - the Americans.
In addition, oil prices went down, which hurt the economy of the Soviet Union even further. This took place because America persuaded Saudi Arabia to produce more oil at a reduced price. This action created more discontent in the Soviet Union.
All of this lead to greater criticism toward the government. Gorbachev also tried to create a government that was more transparent, which lead to more criticism. Internally, the Soviet Union was coming to an end.