I am in the process of restoring a set of Bose 901-V Speakers, which is probably proof of some sort of mental instability on my part. I knew going in that there were 18 speakers that needed re-foaming, so that's not the issue. The hardest part, so far, has been figuring out how to get the grills off. The rear grill is easy; it just pops off. There are 6-8 spots where some type of gummy glue helps hold them in place. It's to Bose's credit that after 30+ years, this stuff is still good, and on this pair of speakers, at least, did not have to be replaced.
The front grill is another matter. I spent a lot of time reading on various sites, and got some clues, but not the total solution. There are 6 staples through the front of the grill, three on each side, that hold it in place. There are also 2 staples on each side of the grill, towards the front, at the top and bottom. These staples are about 1/8 of an inch wide, and fairly well covered with the cloth. I had to use a magnifying glass and a flashlight to locate all 10 of them. Removing them will take a steady hand, small implements, and protection of the wood to remove them. When they are off the cabinet, and the plastic underneath is exposed, you will see that staple locations are clearly molded into the surface. I am thinking that I will replace the staples with velcro, or some type of easily removable cement, just in case I ever have to go back in again.