I have a '47 3100 that I'm bring back into service many of the features.....Wipers being one. My on/off linkage was jerry-rigged with wire and ties. They worked but you had to get it "just right". Nothing quite like crawling on your head and trying to reach up to install those &*^ little grommets! You can barely get one hand up there let alone two to 'press' those grommets in and seal the edges. Now I'm talking about the grommets and the on/off control lever. It seems you are talking about the grommets linking the motor to the actual wiper bases. The grommets and control rod were very cheap, the install....priceless! I'm probably going to remove the motor and disconnect the arms to the wipers to bring the wiper body down to where a mortal can install that little bugger. My first option tho is to try a bit of soap on the grommet to help 'Persuade' it along. ;-)

Tim is right, grommets are easily found and inexpensive. Might be a little challenging to get them in. Good Luck!