Well, I hope persistance pays off, I seem to be unable to edit or delete the previous attempts:

I have a page with ~15 images, each in a property: fig1; fig2; fig3; etc. I'm trying to create a macro with a parameter so I can just change the figure property for each instance I place on the template.

This razor script with no parameter works:

Template:
<umbraco:Macro Alias="ShowFigure" runat="server"></umbraco:Macro>

Script:
<a href="@Library.MediaById(Model.fig1).umbracoFile">
<img src="/imagegen.ashx?width=550&image=@Library.MediaById(Model.fig1).umbracoFile" alt="" />
</a>

If I add a text parameter 'figure' to the macro, and input 'fig1' when inserting the macro into the template, plus replace 'fig1' with 'figure' in the script, it does not work:

Template:
<umbraco:Macro figure="fig1" Alias="ShowFigure" runat="server"></umbraco:Macro>

Script:
<a href="@Library.MediaById(Model.figure).umbracoFile">
<img src="/imagegen.ashx?width=550&image=@Library.MediaById(Model.figure).umbracoFile" alt="" />
</a>

The page shows the ImageGen 'Hello, world!' error, and the source shows no image:

<img src="/imagegen.ashx?width=550&image=" alt="" />

However, if I put:

<p>@Parameter.figure</p>

in the script, it shows the parameter contents correctly, 'fig1' (w/o quotes), on the webpage, so I know it's getting there.

I think I've tried all the possible combinations of "" and [], plus tossing in an occasional '#' for good measure, in both the template/parameter and the script but haven't figured out the magic.

Help!