My Pfaff 919 Hobbymatic was doing the same thing. I have never had a days trouble with this machine, but all of a sudden the presser bar was not holding pressure, and I need to start my Christmas sewing 2010. I cleaned my machine and oiled the lower part of the shaft but I was afraid to oil the thrust pin, (upper shaft) since my handbook says "not to oil my machine". I have been searching the internet all evening trying to find parts & repair diagrams to try to determine whether the presser bar needed replacing and if I could fix it myself. I am thrilled I discovered your comments, a little WD40 on a Q-tip freed my presser bar right up. Praise the Lord and thank you for posting
NormasBrew
November 2010