Help with soap dispenser!

First I would like to say Hello to everyone and Thank You in advance for allowing me into this forum!
I have a one year olt Price / Pfister top mounted liquid soap dispenser . It worked well for 6-7 months . Then it became somewhat erratic, sometimes working sometimes not. Finely it won't work at all. I took it apart and ir appeared to me that the soap was too viscous to be able to be pumped through the supply tube, so I cleaned the thing out and it worked like new for a brief period of time (2-3 days). I am using standard liquid dish soap as always but wonder if there is a special soap to use or is it just normal for these pump type dispensers to be short lived? Any input will be appreciated. Mr. Merle