Honest, it doesn't need cleaning unless you leave it in a VERY dirty environment.
But to answer your questions, that photo tells the tale. There are four screws down through the top of the wood cabinet to hold the chassis in place. Usually chassis slides out the rear, but the photo appears like the trim strip will want it to slide out the front. Once the four screws are out, it should become obvious which way the chassis comes out. Be aware, a lot of times when an amp is made, there is a certain stickiness to the innards, and the chassis might initially stick to the paint or tolex. There are no hidden screws, but the chassis might seems stuck at first.
Yes, you will have to pull the wires off the speaker for it to come all the way out. They are the yellow and blue ones. Yellow to the + terminal on the speaker. The wires are not really soldered to the speaker are they? Some are soldered, but most are push-on connectors like these:
You do have to be careful as they can hold pretty tight, and they can let go all of a sudden when you pull hard, and you whack your knuckles.
The interior photo looks typical. And
there is absolutely no reason you need to dismount those circuit boards. if you want to clean something, put your vacuum cleaner on blow and blow anything loose out of the chassis. Then STOP.
Look rear center, see the white goo oozing out from behind the couple transistors, and note the transistors are screwed to a heavy metal slab and there is a little white goo hiding behind that. the goo is thermal silicone paste, and if you dismount the things there, you will have to replace the goo. it is important to the amp cooling itself.
I can't tell from the picture, but see the flat gray ribbon cables connecting boards together? The connectors on the ends of the ribbons are many times held down with a dab of glue. Also it is VERY important that the ends of those ribbons go onto the connector pins correctly. There are two little parallel rows of pins sticking up from the board. it is easy to get the connector off one row or down one pin either direction, and then circuits blow. You need to know what you are doing. As an authorized service tech, I rarely have top pull a board unless I am replacing a part on it.
All the panel controls with lights around them? Those are really rotary selector switches called encoders, they are not like common volume and tone controls. This amp is really a computer inside.
The schematic is available from customer service at Peavey, but it only shows the circuit diagram and the board parts placement. there is no picture of the chassis or cabinet.
If your amp is working well, I highly recommend leaving the insides alone. Something I teach my trainee techs:
When the amp works, stop fixing it.
