Check Valve Issue? (JCB 1550-B)

I've had this machine for probably 20 years. When I first got it, I changed out filters. I seem to recall when I changed the hydraulic filter, there were small bits of metal in it (on the magnet). Since then, when I change it out, I've always feared more metal bits but instead, I have what I'd call small iron "filings" like dust.....which strikes me as probably more typical.

(that was just backstory)

One thing it's always done and is getting worse.... the backhoe will slowly drift to...

Check Valve Issue? (JCB 1550-B)