Examine the legs and casters carefully. It is possible that all it ever had was 2 casters in front. The sette could be moved by tipping up the back and moving it around akin to a wheelbarrow. Once the sette was put back down, it would stay in place and not scoot around.

If it had 4 casters and the back two are now missing, it would not sit properly; it would tilt back very moticeable. To correct this, either the front legs would have to be shortened, or a piece added to the rear legs. If the front legs were shortened, the seat height would be too low and its valued lowered - maybe ruined- as well.

If it sits right, the seat height seems ok, and there is no evidence of a piece added to the rear legs, it probably had only the front casters when new.

Thanks for the info. The rear legs do have holes on the bottom where I assume casters once where. It does not appear to be tilting. It actually seems fine. Maybe it sit a little forward before?