Thankyou for your replies, new filter, pump filter ok, restriction in tank? not sure, pump ticks very fast all the time, im sure my spartan never use to, not that fast anyway. New pump ordered, looking at new pump flow rates, not found one that pumps as little as 1/L/ min.
It may pump quite well with an open flow but once the flow is restricted it may not be able to pump quite so well.
Diana