Mac416 electric chainsaw : chain stops and rough sound coming form motor: sounds like brake is engaging whenever I put pressure on blade

is there the proper slack in the chain?

Sounds like the chain is not on right. Look in your manual. If no manual. Go to youtube on the line, repair chainsaw

pull back on the forward handle it sounds like the clutch brake is on

If the saw was run with the brake on, or with the brake cover pushed on with the brake on, then there could be some damage to the drum, the clutch, or the pump drive gear that is normally driven by the drum, the lack of oil to the chain could be the same issue as the noise, remove the brake, clutch and drum, inspect all of these components for damage or blueing from heat, if you can pull the clutch shoes out with your hands then the spring requires replacement, check the needle bearing for the drum, if this is dry, then re grease it, check the oil pump drive gear for melting or damage.

no expert..but sounds like the centrifacal clutch went out

Sounds like the blade brake is engaged. You should be able to pull the blade brake handle, located on top of the saw, in front of the top handle, back towards the handle to disengage it. You can find replacement bars, chains & sprockets for your saw at Partsbuggy.com.

there is a broken gear in the gear reduction box. (explain:) the motor spins at a high rpm, the chain moves at a 1/4 or less rpm than the motor. a series of gears reduces the speed, which in turn creates torque, allowing the saw to have the force to keep cutting without stopping. One of the gears is broken or a keyway on a shaft is sheared...as far as i know, no electrical power tools are rebuildable. it's a safety thing (electric shock if reassembled wrong...they are priced for replacement...get a new one...

You have obviously jammed or broken the chain on the inside of the motor. Take it to be repaired, or try reparing yourself by opening up the engine casing yourself.

Check the chain brake safety mechanism, see if it is jammed or see if chain has come out of track...

If the brake is not engaged the only thing it could be is the clutch, or the bar. If the bar is burnt or bent from the chain failing off then you will have this problem. But this sounds more like a clutch problem