Yamaha G50iii 1-12 Guitar Amp - Does anyone have the manual and service manual schematics? Also, how can you remove the top handle to clean it?

I recently got a 1985 Yamaha G50iii 1-2 guitar amp, and it sounds great! Other than being very dusty, it is almost like new.

Does anyone have a copy of the user manual or service manual (schematics)?

Also, does anyone know how to remove these black covers from the handle?

I want to remove the handle so I can scrub dust off of the vinyl really well.

I found a picture of some else's amp (the last picture), which has the black covers removed. Under the black covers, there are silver covers which have a screw holding them to the cabinet.

https://preview.redd.it/9qrv97j3nqjg1.jpg?width=1080&format=pjpg&auto=webp&s=f0fef359fd674e88e622b1ffed4db0ecfaab20ae

https://preview.redd.it/mrsd9er4nqjg1.jpg?width=1080&format=pjpg&auto=webp&s=443cbcdee0258284e97c71251363068e03ae3274

https://preview.redd.it/3vi81fc5nqjg1.jpg?width=1080&format=pjpg&auto=webp&s=4e36815bb635766363ab3eb5df5e525592b5bc78

https://preview.redd.it/wo5wi8y5nqjg1.jpg?width=1080&format=pjpg&auto=webp&s=be4d88b2a19a69d37b26af6e485ae2d09bb9e463