Auto Population

The find is finding the value, the code is backwards.

Try this code: It searches the usedrange, not the entire 16,384 rows.

    Set pnfind = Cells.Find(What:=varPartNumber, After:=ActiveCell, LookIn:=xlValues, _
            LookAt:=xlWhole, SearchOrder:=xlByRows, SearchDirection:=xlNext, _
            MatchCase:=False)

    'MsgBox pnfind.Address    'for testing

    If Not pnfind Is Nothing Then
    Dim LastRow As Long
    Dim iRowCount As Integer

    With ActiveSheet.UsedRange
        LastRow = .Rows(.Rows.Count).Row
    End With
    iRowCount = 1
    Do Until iRowCount = LastRow
        If Selection.Value <> varOperNo Then        'looks for oper no saved form before
            Selection.Offset(1, 0).Activate
        End If
        iRowCount = iRowCount + 1
    Loop
    Else
        MsgBox "The part number " & varPartNumber & " does not exist"
    End If

This message box

MsgBox pnfind.Address

shows the address of the "pnfind" variable.

This leads to the next error.

    ActiveCell.Offset(6, 0).Activate    'moves to new work center number and
    'copies cell value
    Selection.Copy _
            Destination:=SFCTimesNew(x, 12)

The code in Red will fail because there is no value 6 rows down.

Perhaps you can explain what needs to be copied from which cells to which cells.
Seems like you are changing worksheet row/column formats (headings etc.)?