hello，everyone，I am resolving a SARS-CoV-2 spike structure in CryoSparc ，I use blob pick（160-220 diameter），then 2D ，however，interestingly， 2D classfication can not see the S2 domain density，and the density of S1 domain（including NTD,RBD,SD1,SD2）is very clear . Is there a possibile solution? Is there any parameter adjustment available for particle selection and 2D classification? The parameters I have used so far are all default now. Thanks for helping me!