Bobbin tension. Help! I live in the TRNC (Northern Cyprus) where there are no service engineers

Question

Help! I live in the TRNC (Northern Cyprus) where there are no service engineers at all. My bobbin tension on the above machine seems to miss all the time - the lower stitch is looping and not connecting with the upper stitch; timing? I've cleaned it thoroughly for lint to no avail - I'm desperate.