Yes the roller requires stripping from the housing, so that you can get to the axle, there will be 2 main reasons for the roller not to spin, the first may well be to do with corrosion for not being used for years. Put the rollers vertical in a vice, then get diesel in a spray can and soak all around the axle and leave, if it still does not move you can always add a bit of heat.
The second problem could be that the roller has slipped on one of its journals, in this case caution must be observed as any use of ‘whitworth hammers’ could be a costly mistake. Again use diesel to free the roller parts, check whether the slide pin has moved position on the axle, if it has, then a new pin needs to be made. This is not uncommon on warn machines