  Several attempts to discover the FICN signal in VLBI nutation series made
during last years failed. In this paper, we present some results of our further
steps in this direction, unfortunately not successful either. We investigated
several VLBI CPO series by means of spectral and wavelet analysis. It has been
shown that there are several periodic signals with close amplitude around the
expected FICN period without any prevailing one that can be reliably associated
with the FICN. The most interesting for further analysis is a relatively stable
oscillation with period of 800 days, which is, however, beyond the intervals
predicted in other studies cited above. It seems to be necessary to improve
theoretical estimates of the FICN period to make its search in the
observational data more promising.
