You CAN disassemble these devices to clean them however the question of SHOULD you depends on the situation.
If the device is to be used for actual life safety, then no. For those intents and purposes it is not user serviceable, if it’s failing, you don’t repair it you replace it.
If it’s a device in your collection then yes! There is a lot to be learned from disassembling a device to see how it works! Although note that this will void the CRAP out of any warranty that might still apply to the device. Also, it takes a delicate touch. One slip of the screwdriver or just a quarter-turn too tight can and will wreak havoc on the device in question. Sometimes just the act of disassembling and reassembling a device can make it work better. The electrical connections that you take out and put back in have the tarnish scraped off of them, you can re-tighten any pitch/volume screws that may have wriggled loose over the years, etc. A lot of those buzzing Simplex horns have a little transformer of some sort in them that vibrates the speaker cone and makes the earsplitting buzz. When dirt, grease, and/or grime builds up against the cone or the vibrator it can impede normal vibrations and cause the sputtering sound or outright failure. I’ve heard of someone selling rebuild kits for a specific set vibrating horns at one point (I do not remember if it was Simplex or Faraday or whoever) so technicians could replace coils or speaker cones devices but I cannot remember specifically.