Canon mp 140 paper feeding - wont take paper

i have a problem with canon printer (mp140).
i have it for some time now, use it a lot and I do not use new cartridge every time it empties but I refill them.
in last few days i've had problems with paper feeding. it started taking more papers at same time, later it started to give eror code for paper jam when there was no paper jamed and finaly it stoped taking paper at all.
when i turn it on and print or copy, it takes paper normaly 1 or 2 times, and then it looks as if it has taken the paper for print, but the paper stay up while the printer is ''printing''
do you know how to fix this?
help, please!
tnx