I have some picky little guys and I have also found that moving them to a much smaller enclosure and providing a hide box ontop of the aspen substrate helps. Then I just put the pinky in the hide box and avoid messing too much with their burrow. Minimal contact until they get back to regular eating is also a plus.

But I don't think it is terribly unusual for these guys to take a few months to acclimate.

Another option might be dixie cupping with multiple pinkies.

I'd try Chris' ideas first but if they don't work you now have some additional more aggressive steps.
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Mark Huntley
Sand Boa Morphs

Kenyan Sand Boa's
4.1 Rufescens
1.2 Albinos
0.5 Dodoma
2.1 Flame
2.5.8 Normal (orange)
3.4.10 Anery
0.1 Snow
2.2 Hopeful Yellow Snow
0.1 Splash Albino
1.0 Splash Anery
1.0 Orange Stripe 100% Het Anery
1.0 High Orange Stripe
1.0 Yellow Stripe
0.4 High Orange Tiger
2.2 High Orange
2.3 Boston Terriers
0.2 Sooners
8.30 Rhode Island Reds
0.0.15 Tropical Fish
0.1 Moody Wives
1.1 On the fence in-laws
2.1 Rug Rats

http://sandboamorphs.blogspot.com/