after pulling the little hair i have left on my head and trying everything i thought would improve my spindle issue i have stumbled accross what i think is my issue and solution. i had a single wire run from +10v (bob) to +10v (vfd). when i made off the control cable initially between BOB and VFD i just used 4 core,2 for the PWM and 2 for START/STOP, all sheilded. because i needed another signal for +10v I ran a single cable temporarily to test and this is where i believe my problems stem from. i unknowingly had the single cable next to a power cable and by chance moved it during the spindle running on its own and the problem dissapeared. Now i know why experienced builders keep the VFD outside the cabinet. i didn't realise how sensitive these signal cables are. once again a big thank you to Jazz for the time given in relation to this. everyday is a day for school .