I have always wondered since stripping the playfield as to why the red insert is beneith the apron...? I found recently watched a video about playfield construction and now know! 
I have always wondered the same thing, now that you know can you let me know? 
Matthew
AFAIK - from watching the doco (US History channel tour of Stern factory) - its to locate the playfield on the press - which does all the underside holes. I guess they chuck a insert plastic in it just for the hell of it...
Continuing on....All coils now have new sleeves (except slings - these were brass?). Any pivot point - ie rear ramp, hole ejects etc have been dismantled, cleaned and new lube. There is very little wear on any of the metals, which makes me think it is a relatively low use machine. Even the black gunk which usually resides on the underside of the playfield near coils is not there either...
The lovely is helping with regraining all the metals at the moment. Hopefully by tomorrow I should have rest of playfield complete. Have new cliffy to install, new rubbers as well....
