Very difficult. Many times after the plate amp and driver are set in the the cabinet of a new subwoofer, moisture causes the wood to expand, and this can really squeeze these components in there, especially when there is very tight tolerances already. So the enclosure itself it pressing in on these components with a death grip. There are some techniques I have learned in order to deal with this, but it still takes some muscle.
I hope you guys appreciate the lengths I go to give you all a peak inside the cabinets!!