i had the same issue with my Speckles.. i tired a cloth feeding bag, placing it in the cage, with the sand boa in it with the pinkies.. then place a small towel over top.. leave it for a few hours, then check..

i am not an expert.. this just worked for me..
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Cilene
2 kenyan sand boas
2 redfoot tortoises
3 box turtles (florida, eastern, ornate)
2 sulcata tortoises