Isofix seat fixings

[snapdragon]

Howdy, can anyone advise on these isofix yellow bars on the max-cosi base.
I just can't get them to engage as they seem too thick for the non-existant gap in the seat and they they just grip on the leather and scrunch it up. There are definately isofix loops in place as earlier in the thread.
Can anyone confirm those guides 8L0019233 help or are they just as hard to insert>
Thanks.