I think I've mentioned that my volume level is stuck

I need my 404 but I'm not in a spot where I should be spending extra cash if I don't have to.

Should I open it up and take a look at it, try to see what the problem is before handing it over to someone ?

I heard that opening it up and blowing dust out may be a fix... also I would just like to attempt to identify the problem incase someone tries to scam me and also just to get a look inside and have a learning experience... just don't want to fck anything up

Seek out pictoral instructions first. Use other people's experience to benefit you.

As well, make sure you prepare a good area to place screws where you can label them and where they go (i.e. use a piece of paper with a crude drawing and label the screws (layer 1, outside, etc.) then point to the picture you drew so you remember where the screws go.

Don't forget to take your own pictures if you cannot find picture step by step for disassembling one.

Be careful of wiring. Many wires of high gage can be snapped easily or even pulled from a connector that has a weak crimp.

Mostly, just think of everything you might find in there, and take precautions to both avoid damaging them and reassembling it back together properly. Usually people do one and not both of these things...reassembly is important!

If nothing I said has scared you at all, then by all means, go for it. If it made you a little unsure about the results of your action, then wait.

I've worked some magic on synths/electronics with Deoxit...google it.
Its just a spray that "improves electronic connections"..pretty safe.
Also I recently took apart my SP555 (pad 13 was not working) and did the add-scotch-tape-to-the-sensor trick (to trigger easier) and it's working like new now. It was a pain but not really that bad to dis/reassemble

I second the spray it with electronics cleaner option. This really has helped in the past with all my instrument's knobs that either get crackles or one that stopped responding.

I did have to replace the volume knob on my sp-303 and it worked great. I desoldered the old potentiometer and soldered in a replacement. To figure out that the pot was the problem, I used a short wire to connect the outer two contacts on the knob, which gave me what the true volume of the device was (because it bypassed the volume control). So you could try that since I don't think there is any way to damage the device, but the problem is that the 303's contacts are much easier to reach than the 404's.

Where do you send SP's to get fixed? Roland or a third party?

I found a few third party service guy through Roland.

About spraying with electronics cleaner, I am picturing having to open it up to spray it to, correct ?

I'd first try just taking the knob off and spraying down the slight opening around the pot. Aresol cans usually come with a handy straw attachment for more precise aim. I would spay, turn the knob from min to max for 15 or so seconds.

If that does nothing, then yeah you'd have to open that sucker up and I don't know how sensible that is since thats the hardest layer to get to. If the third party quotes you a good price, I'd recommend that at this point.