If c+d say there aren’t good blocs available I’d believe them, which means you will have a problem finding good ones
.....in my experience c+d would rather be out of stock than sell poor quality parts, unlike less reputable suppliers (who will tell you “take it or leave it it’s all that is available in the market”)
Your pic looks like the blocs you bought were old stock, a bit of very old looking rust there?
Bronze bushes like muskrat says is a good solution but you will need to get the “end float” control right, something (eg bronze washers, top hat Bush) needs to stop the side to side movement of the swing arm to a minimum, whilst allowing the spindle to clamp up tight as it does with blocs. The custom machining involved could be pricey.
Alternatively I guess you need to try to find a supplier whose stock is a few years old, before the supply chain became dodgy, the risk being you get more duff ones.
I suppose it’s not too surprising if usable blocs became unavailable, if they are made especially for bsas and can’t be adapted from a “standard” bloc used in larger volumes, the sales volumes for bsas can’t be high!
