VJ 1204 - How do I replace the rubber wiper?

It just pull it out. Hold the wiper holder down and pull straight up. Sometimes a little hook made out of a paper-clip is handy to pull up from the bottom. There's a little hole in the wiper that fits over a tab in the holder. Once you get the old one out it should be clear how the new one goes in.

 

here's what you do.

you are going to pull the wiper up and cut the two rubber pieces, then the wipers pulls out and then you are going to firmly press the new wiper down.

after you installed the wiper, take a clean swap with cleaning solution or ink, and wet the damper. this softens the rubber and gives it a little lubrication for the first pass.

 

Either of these methods should work.
I personally have not changed a wiper in a 1204, but Valentinos dwg would seem to be correct.

Normally, these get pretty soft over time and will just pull out.
Stiffer ones may require a very small blade (jewelers screwdriver)to push the 'holes' away from the hooks. Too much force here will distort the holder, so be careful.

Valentino, thanks, I would like permission to use your drawing for our knowledge base.
I am at ISA this week, but I would like to add this when I get back.

 

You only change the wiper on a mutoh once a year?
I change em on my Mimaki every 2-3 weeks.