How do I release stuck chain brake? (Makita DCS6421)

[Jack Smith]

Hi. After having determined why my chainsaw didn't sound right (thanks Arborsite members!) I set out to get my chain break unstuck. However,
after removing the side plate and looking at the mechanism(s) I'm not sure what to go from here. I made a short video that shows the chain brake
mechanism. Can someone check out the video suggest what I need to do to get the chain brake unstuck?

 

[irhunter]

My shoot-from-hip:

I would (1) make sure I had the shop manual and IPL for the saw, and (2) take the chain brake assembly apart. I suspect you will find a worn/hogged-out metal-to-metal part.

You get the manual and IPL by asking for them in the Beg For Manuals thread.

Roy

 

[blades]

looks like a makita/ dolmar unit, lot of sparkly stuff in there. going to,take some digging to replace. what ever is around is going to be new old stock or used. Makita has abandoned gas units completely.

 

[huskihl]

Are you certain the brake isn’t hitting the cylinder top cover?

Pull the brake harder?

 

[holeycow]

Can't you just take out that little "keeper" screw and pry the band out of there? A little tugging on the band with a blunt pick around the drum might get the band out. Then the rest of the mechanism will be loosened up.

Or not..

 

[Bob Hedgecutter]

Put all the covers back on so nothing pings off around your yard never to be seen again. Place the saw on firm ground. Reach up front and pull that big plastic hand guard looking thingy forcefully back towards the round handle that your left hand holds on to- I mean forcefully like you are pulling a bad man off of your mother.
When you hear/feel the mechanism click back into place, retaining the spring pressure- release your grip on the handguard.

 

[holeycow]

I assumed he had already tried that...but you are probably, most likely exactly right.

 

[blades]

what looks like a lot of metal shavings all over suggests the brake band is shot or clutch is badly worn. before honking on it I would try to flush all that material out of there. years ago i had a 116si that the band was shot on but the mechanism worked as far as locking back was concerned. have not experienced any problems with my 7900,7910, 6400,6410 or the older 50 cc unit which I can remember the model number of ( 3 digit) in the break area to date.

 

[huskihl]

It really looks to me like you’re trying to push it forward. The brake needs to come back to release

 

[Jack Smith]

Thanks guys. I'll go back and give it a good tug as Bob suggested. I didn't even notice the metal shaving bits around the mechanism area that Blades pointed out. I'll brace myself for a shot brake band or clutch - thanks Blades.

@holeycow - I'll take a look at the "keeper" screw that you mentioned. @huskihl - I'm pretty sure its not hitting the cylinder. I'll be sure to take a closer look.

The chainsaw is actually at a relatives house so I'll need to make the trip over to assess the situation again with the information everyone provided. Thanks guys. I'll be sure to come back and share the results.

 

[stihltech]

If you are pulling the hand guard back and nothing is missing, the end of the spring looks to have a slot in it, is this correct? Are all pivot pins tight? Any wear in the hand guard where the linkage attaches?
Oh yes, please clean it all up before proceeding as stated before.
Magic wand at the ready

 

[Jack Smith]

Fixed it guys! I think Bob and Huskihl were right when they thought I might be pushing the brake in the wrong direction. Just glad I posted in the "101" forum here rather than an advanced section of the site

I'm actually not quite sure what I did, though. I cleaned the area with a toothbrush and paint thinner but managed to make a pin come loose. After I put it back in, and once cleaned, I brought the chainsaw outside and fired it up. Everything seems back to normal now. About the pin, I guess I need to tap it in place a few times so it doesn't become loose. Below is an image showing the missing pin, as well as a video that shows the working brake.

 

[blades]

Always like a inexpensive happy ending.

 

[Jack Smith]

Yes, absolutely! Thank you!