I fixed it!   

All it was was a screw holding in the frame to the chassis. It was loose, causing the gears to not fully mesh, and thus grinding against each other.

Thanks for the help everyone! 

Quote from: WoundedBear on August 03, 2018, 12:41:27 PM
About all it could be is a stripped, cracked or split gear somewhere. You are going to have to check each one for hairline cracks.

When it's apart, apply power and then put a load on the mechanism and see if you can find a at is slipping. Bachmann parts has lots of stuff for these models.

Sid

I made some progress dissasembling, and took off the main drivers off the valve gear. Both gears seem to be flawless, no cracks, strips, anything. When I applied 9v power to the loco and pressed on the wheels, only when I applied medium pressure could I get the gears to slip. It seems that the wheels and axle aren't seated further down enough to mesh and make full contact with the other gear. I don't know why this would be, as this loco has been working fine for me for a while! The worm gear and first gear DO NOT slip for sure, if a gear slips, its the one on the axle of the main driving wheels. All the screws were tight on the locomotive when assembled, and only exhibited this problem when I attempted to pull a load yesterday.

Please help with this problem as its getting kind of frustrating. 

Thanks for the reply.

I applied power to the mechanism when apart, and put load on each of the pairs of the wheels. It did not want to slip when I applied pressure to the main driving wheels, but slipped when I applied pressure to the farther- away wheels. I think It may be a worn down gear.

I have a Bachmann 2-8-4 Berkshire locomotive that has been working fine, untill recently, when the gears started to slip. When I put 5 or more cars behind it it makes a "cccrrrccccrrrccc" sound, and the wheels dont turn. I dissasembled the loco, but could not find the problem. All screws were in tight, and everything was greased/oiled.

Please help me fix this problem!!