Diminished chords for left hand

[Pipemajor]

Now that I've changed over from PA to CBA I'm starting to make some progress at last.
Both my CBAs , a Maugein and a Paulo Soprani, I bought in France and neither have the usual 6th row of bass buttons for the diminished chords. I'm now finding that these diminished chords are beginning to crop up in the tunes I'm trying to play and I have difficulty in finding suitable substitutes.
Although the Hans Palm site appears to have gone I've found other sites with various means of playing non standard left hand chords but none cover diminished chords.
Has anyone else had this problem and found a way round it :?:

 

[debra]

Many (but not all) accordions that lack the row with diminished chords have a different setup for the 7th.
A C7 normally has C-E-Bb, so it is missing G. On an accordion without diminished the C7 is E-G-Bb, thus missing C.
By doing this the C7 can be used as Gdim.
Note that all accordions (I know) have a 3-note diminished chord, so to get the full diminished you need to combine two: Cdim = Cdim+Adim, Gdim = Gdim+Edim, Ddim = Ddim+Bdim and all the others are repeats because there are only three diminished chords.
To get a complete 7th you need to combine major+7th, whether you have the normal seventh or the alternative that needs to double as a diminished.

 

[Pipemajor]

Thanks Paul, I had a feeling that the 7th chords sounded different on the PA to the CBA but my ear isn't good enough to tell what the difference is. As the C and G are next to each other it should be easy enough to use the next row accross for a diminished chord. I'll try it out and see if it works on my accordions.
Thanks again. Ian