Digital BW, The Print

I want to clean the underside of my 1160's printhead because I'm 
experimenting many bad nozzle checks just after adding some MIS FSN-K 
to my CIS system (the ink in the CIS bottle was FS-K but rzeiss from 
MIS told me that it's the same ink used in FSN-K). Actually the 
phenomenon looks like starvation not clogging - different nozzles 
won't fire on each try and it goes worse after every cleaning cycle. 
I tried to raise the K bottle by 1/2 - 2/3" but it didn't helped. 
Then I returned it to the original height. Waiting overnight seems to 
solve the problem but when I let the printer power off more than two 
days all the above scenario repeats. If you have suggestions to solve 
this problem I would like to hear them.

Now, the original question: I want to clean the underside just to 
eliminate the probability of underside ink residue being the problem. 
I have access to ammonia (we don't have Windex in our area) - will 
buy it at the pharmacy. I want to do the papertowel trick, should I 
dilute the ammonia from the pharmacy? If yes, what should be the 
ammonia:water ratio?

Thanks in advance,
Loris.