Britax 1st Class + in Ford KA - wobbly. Help!

[LaTristesse]

So I got the MiL a 1st Class Plus for her KA for the days she has DS. I installed it behind the passenger seat, forward facing, using the regular seatbelt method and as far as I know I followed the instructions ok, but it seems very wobbly, particularly if not reclined and when nudged from the top.
Has anyone else had similar issues, or can you suggest what the problem might be?
Thanks

Take it to a shop with the car and get them to check it is in right. There may be a video online on the britax web site on how to install it

If it is installed forward facing the lock off clip should keep the seat rock solid. The lock off clips are situated either side of the seat (you use the one that the on the same side as the seat belt is situated - never both sides).

If you feed the seat belt through it and then press the lock off button down and pull the seat belt tight making sure the lap part of the seat belt is also tight it should be so solid that you can shake the seat and get no movement (you may also need to have someone press down on the FC's seat to give a bit of pressure to pick up the last of the slack in the belt).

HTH

Thanks Truthsweet... I'll check that -seems the likely culprit!