There is nothing wrong with a chain drive primary if it is properly set up. Tensioning the chain by the adjuster on the mounting plate as most manuals suggest is wrong. This is what will break the rollers on the chain and deposit them in the bottom of the case. Sound familiar?

…it may well be worth it to inspect and clean it.

Do you have blue smoke from your exhaust? Are your riding buddies always making you ride sweep because you keep smoking them out? This may be a solution for you.