8 months ago, I bought a Flex 3401 to avoid reliability issues with other models like the UDM. I was fully aware of its limitation, like its fragility when applying too much pressure on the extremities. I think this wasn't enough because 6 months after the purchase and around 5 jobs later, what looked like a tiny plastic ring came off the plate. I ensured that the Allen bolt was tightened properly and everything was perfect. I therefore completed the job flawlessly, without a single sign of abnormal wear. Today, 2 months after this incident, I decided to open the Flex and see what was going on to be sure that there was nothing wrong and that I'd be ready for the next jobs. The first noticeable thing before removing the plate was a very minor backlash up and down; maybe 1mm. After opening everything, here's the result: I really don't think this is normal; is it? Should I send it back? Is this typically covered by the warranty?
The rust bolt could be from some moisture that crept in there from one of your damp pads perhaps ? The backing plate looks as if it has been slightly melted as a result of friction with the felt rind where the backing plate attatches ot the machine. I would suggest a drop of oil on the felt as recommended in the various 'Flex rash' threads on here and other sites
I would say the rust is normal. Almost all my power tools including my Makita 9227C has various rust spots. I've got a couple ancient cordless drills that have rusted chucks but still work like they are new. It is just character ;-)
Ok, so I got the replacement parts (backing plate and ring gear). Looking at the ring gear, what could have caused this damage? My warranty is ending soon. If it's a bearing, I'll try to get it replaced now.
A quick update! I contacted Flex and they sent me a felt ring, ring gear and backing plate. I was still worried about the internals so I sent the unit to a repair center in order to get the unit inspected. They changed a bearing. It looks like part 259.148 on the diagram. I don't think they changed the needle roller bearing.
