There are six (6) wood screws holding each double spring unit onto the chair. First install the two (2) wood spacer blocks shipped with the replacement unit into each end of the old unit. This will prevent screw tear out of the wood while the screws are being removed making new spring installation more difficult. After removing the upper and lower screws, hammer remove the wood blocks from the old unit.
Install the wood spacer blocks into the new spring units by force spreading apart each end creating a space for the blocks. Placing the spring unit lower 3 screw holes into a vise will make installing the block easier. Use a screwdriver or wrench for leverage on the unit and pry open enough to get two corners of the block started. Then hammer tap the block in all the way and repeat for the opposite end. The unit should now be spread apart the proper distance and screwholes should line up to the original installation holes. Install and tighten screws.