I've read this thread with great interest and thought I would add my recent finding with the trouble with my SD255 bread maker and may help others in years to come.
The problem was the motor run capacitor.
This component in my case did not fail overnight like an on/off switch. It was more gradual.(over years)
The size of the loaf started to shrink and like everyone else, assumed that it we were doing something wrong.
By changing the ingredients we could improve the results, whether that be Canadian Flour or adding Vitamin C but
the underlying problem was still there. I found that by using the rapid bake option the results were also better but again the problem
was still there...and getting worse. Until eventually we stopped baking altogether as the bread from the shops was simply better.
Like user R765 mentioned on here, I purchased a replacement capacitor (N40KG) from Maplin 3.59 pounds May2016.
You can get these cheaper from china but for the sake of a pound or two, do you really want to risk a fire from
an unattended bread maker? because not all of these capacitors are subjected to the necessary tests we expect here in the UK.
The Maplin component is better than that used originally by Panasonic. The original capacitor is rated up to 75degs C.
The Maplin component is rated up to 85 degs C. I've no idea how hot it gets at the capacitor but another 10 degrees can only help the overall reliability.
This component comes with two wires about 4 inches long. Simply remove the old capacitor block (grey in colour in my case)
and solder in the leads. It does not matter which lead is soldered into either circuit board hole.
In my case, the capacitor fitted very snugly into the white Panasonic plastic case. If the capacitor was 1mm taller then it might not have fitted.
The results are instant. No more being fussy with ingredients or adding vitamin C. Excellent results every time, which is just how I remembered years back.
In terms of the old capacitor, there are no visible clues of trouble, it’s not black or swollen in appearance.
It does not smell or make a sound. The only clue is ultimately a poorly mixed bread loaf, which is then cooked
and appears small and heavy in density.
I've read the entire email thread here and although just about all is true there are a few red herrings mentioned
such as stiff spindles in the bread pan.
So as a check, you may want to do this test.
With the bread pan out, start the bread maker with the program pizza making for example.
What we are trying to do is start the program by going straight into a mixing operation.
With your hand on the black spindle inside, try to determine if you can stop the spindle from rotating
with minimal effort. i.e. almost with one finger.
We are not trying to stop the spindle from completely turning, we are trying to feel/gauge the power.
So in my case, it was fairly strong for 0-20 degrees rotation, which is not a lot, and then the power dropped right off to zero before the next power pulse..
So I knew that it was not the bread pan causing the issue.
With a good capacitor, the revolutions would be considerably more than 0-20 degrees. perhaps as much as 2 complete revolutions between pulses.
Another point I can mention is that this bread maker will work fine with a 3amp fuse fitted in the plug.
So if yours has a 13 amp fitted and it might have as standard from the factory, then you might like to swap this for a 3 (three) amp.
All this means is that the fuse will blow quicker if a fault is detected and thus technically is a bit safer. The bread maker should not use more than 3 amps.
Wish I had found this thread ages ago....well done R765 for the initial post!
Hope this helps..........