Hi everyone hope someone can help have just bought a daf 45 130 turbo horsebox that failed mot a couple of jobs

The brake test was as follows

service 48% FAIL

secondary 26% PASS

secondary 22% FAIL

parking 15% PASS

Basically it says service brake low effort and secondary brake low effort. The lady who i bought it from has had the following done

Replace brake pipe to load valve

Free off load valve

new rear adjusters,new shoes, new handbrake cables, set up brakes and handbrake and bleed brakes

The handbrake when released takes approx 30 seconds to release when let off and front brake still has low effort just wondered if anyone has any suggestions they can give as to the possible cause I am very handy mechanically but have never worked on air brakes before. Help please thankyou