It sounds as though you are trying to merge single records into a merge
letter. One easy way to do this without recourse to vba or leafing through
interminable menus is to add an ASK field and a SKIPIF field to the very
start of the merge letter. These don't print so take up no space.

If we assume that the policy number you wish to search for is in a field
called 'Number' then if you merge *all* records, the following will print
only the record that has the matching number.

{ ASK  Policy "Policy Number" \o }{ SKIPIF { Mergefield Number } <> { REF
Policy } }

You do need to ensure that {Mergefield Number} does in fact reproduce
exactly what you enter in the ASK field or they will never match.

When the find record facility doesn't work, another possible approach is to
enable the Mailmerge toolbar (e.g. View->Toobars), then use the MailMerge
recipients box (3rd button from the left) to display the record list, scroll
up and down to find the record you need, then click it and close the dialog.

It's obviously not the easy search facility you need, but it probably will
work as long as your Excel sheet does not have more rows than the dialog can
hold (And its maximum is not huge - it's either 1000 or 10000 records, I
forget which off the top of my head).