KillerBee Linear rail issue - Am i being fussy?

Morning all, I have a ooznest workbee which I have bought the ratrig upgrade kit for. I have started installing the linear rails on the long y axis as per instruction, but they dont feel like they glide at all, you have to push it and you can defo feel parts of the c beam which has more resistance than others when you manually run the gantry mount up and down the linear rail. I have tried loosening both linear rails and centralising each end and working my way along using the gantry to space the rails then tightening the t nuts, ive also tried working my way out side to side from the centre but will the same result. Is it normal to have some resistance? just worried about it putting strain onto the stepper motors. Sorry for the long post. Any help would be most appreciated. Thanks

If the rails are preloaded (which they should be for CNC use), then they should feel a bit tight, but smooth when they move.

Hi m_c,
the rails slide fine when they are on their own without anything bolted to them its just when everything is assembled, i think the c beams may be bent, or the steel side brackets may be slightly out or something. Was wondering if there was any tips and tricks