Remove the four side screws. The amp will slide out the back. Lift the rear chassis while pushing on the front control panel. If the rear wood panel is in place sometimes it can bind against the cabinet. If so, remove it first.This can be easier if you do it on the floor or a good sized work bench.
Once the chassis is removed, you will see how to remove the front panel, there are side screws and one at the middle bottom.
The grille cloth is stapled on, a paper staple remover amd small sized pliers will help. Clean up the frame, it can get grungy. It'd a good idea to glue on a piece of black fabric store felt (it's about 1/16" thick) onto the front of the frame. Then use a razorto trim all the edges and where there is an opening. Then cover it with the felt. The felt adds some padding under the cloth and makes it look better.
When putting on the grille cloth, you want even tension so that it isn't wavy. People have different techniques for doing this. Like to carefully align the lines of the cloth so that they are parallel to the top and bottom of the frame edges, then clamp the frame and cloth down. This locks it in place. Then you can fold the cloth over and staple it in place, one edge at a time. You need to use a hardware store stapler, not one used for stationary.
When applying the grille cloth, if it doesn't work the first time, don't worry. Remove it and restaple it. Not a big deal.
When done, if you want to tighten up the cloth, you can shrink it with heat. The heat needs to be applied evenly, otherwise you can get wavey lines in the cloth. I like to heat the oven, open the door and hold the frame in the front, not in the oven, and let the blast of hot air hit the frame evenly. Keep an eye on it and move it back and forth in front of the oven to regulate the temperature. Repeat the process if one shot isn't enough. Some do this with a hair dryer but the heat will not be evenly applies over the heat entire cloth. Be careful though, too much heat can melt the cloth. Do not use a paint stripping gun.
