Just fitted some nikone brake seals the other week was fine to start with but not the same lever feel .... then thursday was out with a mate on the bikes and one let go

anyone else had experiences with these parts ? going to temporarily fit the old seals as there was nothing wrong but i had just painted the calipers, which are ruined now and also powder coating on the front wheel, balance weights fell off .......... and tyre is covered in brake fluid
note to self buy oem seals