Turn one row into multiple rows in Excel

I have multiple items that are available in multiple distribution centers (i.e., a many-to-many relationship). There is currently one row per item, with one column for each distribution center. A cell in the row for item X and the column for distribution center Y is marked with the code for distribution center Y if item X is available there and blank otherwise. An item with multiple distribution centers will have multiple distribution center codes (in their respective columns). So the current sheet looks like:

    |   A    |         B         |*|                      S-AJ                      |
1   |  ID #  |   Description     |…|              Distribution Centers              |
2   |   17   |   Ginkgo Biloba   |…|      |      |      |      |      |      |  SE  |
3   |   42   |   Ginseng         |…|      |  MP  |  MS  |      |  NW  |      |      |
                     ︙

Columns C through R contain other attributes of the items, such as UPC code, cost, and price, which are not relevant to this question. My actual sheet has 18 distribution centers, spanning columns S through AJ; I reduced that to get the example to fit into Stack Exchange’s window.

I need to have a single distribution center column, with a single distribution code per row, and then duplicate the rows as needed for items that currently contain multiple codes. The result should look like:

    |   A    |         B         |*|   S  |
1   |  ID #  |   Description     |…|  DC  |
2   |   17   |   Ginkgo Biloba   |…|  SE  |
3   |   42   |   Ginseng         |…|  MP  |
4   |   42   |   Ginseng         |…|  MS  |
5   |   42   |   Ginseng         |…|  NW  |
                     ︙

where cells A3:R3, A4:R4, and A5:R5, contain the same information.

The only way I can think of doing this, which would be time consuming, would be to copy the item number into multiple rows; and in the column that has the distribution code I would change code for the item that is available in each distribution center. I will be doing this for 900 items. Is there an easier way to do this?

1. Create a new sheet.  Copy the header row(s), the column widths, and the formats, except do not copy Columns T-AJ.  It may be easiest to copy the entire sheet, then delete all rows other than 1 and unmerge Columns S-AJ.

2. First we want to replicate each item row from Sheet1 onto Sheet2 18 times — once for each distribution center.  Type =INDEX(Sheet1!A:A, INT((ROW()-2)/18)+2, 1) & "" in Sheet2!A2.  INT((ROW()-2)/18)+2 maps rows 2-19 on Sheet2 to row 2 on Sheet1, rows 20-37 on Sheet2 to row 3 on Sheet1, etc.  The & "" causes Excel to display a blank when referencing a blank cell in Sheet1.  If you don’t have any blanks in Sheet1, you can leave this off.  If you don’t like this particular solution, you can use one of the other solutions from Display Blank when Referencing Blank Cell in Excel.

   Drag/fill this to the right, to cell R2.

3. Enter =INDEX(Sheet1!$S:$AJ, INT((ROW()-2)/18)+2, MOD(ROW()-2, 18)+1) into Sheet2!S2.  This references the same row in Sheet1 as the above formula, but Sheet2!S2 gets the value from Sheet1!S2, Sheet2!S3 gets the value from Sheet1!T2, Sheet2!S4 gets the value from Sheet1!U2, etc. This will display 0s for blanks.
4. Select the entire row A2:S2 and drag/fill down to get all your data.  This will need to be 18 times as many rows as you have on Sheet1; i.e., 18×900=16200.
5. Copy all of Sheet2 and paste values.
6. Filter Column S.  Display only the zeroes.  Delete all the rows (other than row 1).  Remove the filter.

Done.