Dan Daniel
Subscriber
It's worth you cracking open your Yashica A and taking a look at the mirror. If it isn't pitted to hell and flaking, then give it a go at cleaning.
FYI, you can get a good look at the mirror in a TLR by opening the focus hood and looking in from the front of the viewing lens. Often very easy to see the tarnish and flaking, especially on the edges.