Challenge MC 305 Clamp stuck down


New member
I am new to the forum. I have a Challenge MC 305 cutter that has the blade stuck in the down position and will not come back up. This happened a couple of months ago and I used compressed air to blow the switches out. It then worked for a couple of weeks and did it again. I then replaced the switches and contactors in the switches. A month later the same thing happened. Was it a coincidence or do we have something else going wrong?
The motor runs when you turn it on, the pump pumps and tries to put the blade down when you press both switches in but once you let off of the switches the blade should go back up but the pump does not even try to pump the other direction.

Mustard yellow
Microcut Jr

Any help would be appreciated.


Well-known member
I have a couple Challenge cutters.. Titan and an XG. Hydraulic. I don't know yours but.. I assume it's hydraulic too.. There are valves that control the pressure. The pressure is applied both directions.. Up & Down. There may be a bit of debris in a valve, like pieces of a seal deteriorating.. Or a cylinder limit sensor moved out of place. Any error messages?


Well-known member
If you've replaced switches and the pedals aren't doing anything, it's almost certainly your hydraulic pressure. It looks like Challenge recommends:

Checking the limit switch, increasing clamp pressure reducer valve setting, replacing clamp down solenoid, replacing power pack relief valve/outside relief valve, checking knife adjustment on up limit switch.

The manual also recommends draining and replacing the hyrdo fluid every once in a while. I know most shops don’t ever do that. I’d start there.



New member
I fixed the problem by removing and cleaning the solenoid (which was full of oil) on the left of the valve body. There was 120v running to the solenoid but it was not engaging.
Thanks for all the help and comments.


Well-known member
Hi sir

Will be a good idea to do this 2 things;

With my Strong experience as Electrical/Electronic Professional Engineer, and working with Polar+Schneider+Wohlenber, Challenge, and others

1) Please refill the recipient with a Good Hydraulic oil, FULL.....!!since the system, is possible as Air, by lack of oil, or leaking in the system, and of course clean the Oil filter or replace it.

1a) the blade must be in Good conditions

2) After that, BLEDDING, the system, until ALL the air is coming out.

3) Please indicate me the ID plate of his machine .

Let me know, Sincerely

Mobile+WhatsApp;+505 8861 1441

Managua, Nicaragua. Central America.


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