Part I Computation of Surcharge was introduced in 2010. There should be no surcharge amount for clubs, since the "Gross receipts" from line 1 would need to be over 4 million for anything to be listed.
As for lines 20 and 23:
Generally, it's expected the two lines to be the same for an investment club. However, if your club entered any transaction as "Other Income" it would be included in line 23 but not in line 20. The program does not treat "Other Income" as investment income.