Hello,
The Arcadia tube is perfectly fine, it should help a lot.
You had mentioned the old owners said the head twitching had been present with them? He has likely had poor UVB exposure
for awhile & his 25Hydroxy levels or D3 storage has been declining for awhile. It can take awhile for the levels to drop to a point
in which external signs begin to show. So far, he has been lucky he hasn't had more issues but I think if you can get better UVB
lighting for him that he can make a great recovery for you. He looks alert in the picture too & happy.
Let us know how he is doing.
Tracie