I have an '80s electronic organ and have agreed to sell it come the end of this week. I dropped something inside it this morning and tried to take it out and noted that the organ is incredibly dusty on the inside. I have had this thing in my house for eleven months; who knows how long the last owner had it. Could it ever become a fire hazard this way? What should I do to clean it?
(This answer is written from the perspective of general knowledge of electronic equipment and is not specific to electronic organs.)
Historically, vacuum-tube electronics could more readily start fires due to poor ventilation because each tube necessarily generates a lot of heat (containing a hot filament like a light bulb). Modern semiconductor-based electronics doesn't contain deliberately high temperatures like that — the parts would start failing from heat well before they are hot enough to start a fire, unless there is some kind of sudden power component failure (likely in the power supply or speaker amplifier), which can produce arcs and flames.
In that case, the question is not whether the dust will trap heat to start a fire, but whether the dust will itself catch and sustain a fire. I wouldn't worry about the amount of dust you show, especially as the power supply section in the top left looks cleaner.
If you feel like cleaning it up, there's nothing wrong with removing dust (and a future service technician might well appreciate it), but you should make sure not to tug on any wiring (in case of breaking connections), and do not apply a vacuum cleaner to circuit boards (this can cause electrostatic damage) — a "canned air" duster spray can is the standard way to remove dust from circuit boards safely.
For the benefit of the equipment, the most important thing to keep clean is any heat sinks, such as the finned aluminum block visible at the top to the right of the power inlet. Keeping them free of dust helps ensure they are most effective at removing heat from the components they are attached to, which will prolong their life.
THAT'S not dusty! THIS is dusty! (And by no means unusual.)
But sure, clean it out. Don't use a vacuum cleaner on electronics. Static electricity can build up on the nozzle and cause damage when it sparks across. Professionals blow dust out with cans of compressed air. I normally use a paintbrush plus personal blowing. Mind your eyes when the dust flies out!
Once all the dust bunnies are out, you can vacuum them off the floor if you like.
But you don't have dust bunnies, and the heatsink seems clear. There's no hazard.