Digital BW, The Print

Hello all,

After years of work without any significant problems my printer got a 
serious clog. It was loaded by MIS UT7 inkset, when I discovered that 
I lost two nozzles (Cyan and Light Cyan) in the middle of page. 
Before that printout nozzle pattern was perfect. I didn't get nozzles 
back after number of cleaning cycles, then treating with Windex on 
the rest pad, then after loading two carts with MIS Fluid and doing 
cleaning cycles with it... I see some traces of clean liquid when I 
print purge pattern with cleaning fluid, but when I change back to 
ink, both nozzles are still clogged. Worst thing is that after 
cleaning cycles my other nozzles are going bad too.

Questions: is it possible that this part of pump that is doing 
suction is too dirty and makes things worse during cleaning cycle? If 
it is, could I clean it somehow? Is it possible to disassemble the 
thing and do a good cleaning of this pump? 
Is it possible that UT7 Cyan and Light Cyan turned bad after 2.5 
years in the bottle?

Thanks in advance,
Sergei