you may have already gotten a reply, but the switch also has an integral circuit breaker, so it is more than just a switch.  I had mine turn off once due to a power surge. the line fuse is a sort of last resort safety thing, the power switch will click off first usually. just replace the switch and that should solve it. I wish I could tell you where to get a replacement, but I'm sure astron can provide one. 
73 and good luck
Michael  kb7nla
On Mar 7, 2011, at 8:58 PM, Lou Kolb wrote:

> As long as we're discussing power supply issues, i've just had an experience 
> I never expected.  My RM-35 from Astron failed and, oddly, the problem 
> seemed to be in the switch.  You'd think it would be somewhere farther along 
> in the circuit.  I was on cw and started to hear an odd sound every time the 
> transmitter in the k3 keyed.  Like an arcing but different in that it wasn't 
> a snappy sound.  At first, I thought it was the rig but then the transformer 
> in the supply started to jump occasionally, as it does when you first turn 
> the supply on.  When I started to smell smoke right after that, I hastily 
> signed and reached up to turn off the supply but the switch wouldn't throw. 
> it moved a bit but was actually fused in place.  Later, when I came back 
> down to the shack it had cooled down and was very firmly fused in place.  I 
> had another, older Astron on the shelf so I hooked it up and was back on the 
> air the next night.  I haven't taken the cover off of the stricken supply 
> yet but it oughta be interesting.  It's not a complicated device so I expect 
> to be able to fix it.  Anyone else have a similar experience?  Lou  WA3MIX