I bought a nice little cs400 ECHO for $30 at a yard sale. Owner said he put a new bar and chain on it but it wouldn't turn the chain. Looked just like yours. I put a new sprocket on, used it pretty near a year then sold the saw for $165 or thereabouts.
Check the bottom of your chain for damage and make sure the bar rails aren't sloppy or damaged and or the bar tip sprocket isn't wore down, sloppy or stiff.. You can compare to new,post good pictures here, or somebody local might be able to assist u. A new chain or 2 and sprocket at the same time is a good practice. They wear the same together and roll with less resistance and chain stretch . A stretched chain also will climb high on a new sprocket wearing it prematurely . Every thing else can run and work perfect, without a sharp chain and efficient drive system its not a very effective way to cut wood so don't pinch penny's when it comes to those parts.
