No, if you want it fixed, you will need to replace the whole unit; although you could always try your LBS's to see if they have any scrap ones which you could try to salvage the parts you need.

If you can replace parts, you can find the part numbers on the EV docs, as linked to here SHIMANO Dealer's Manual / User's Manual

In the case of the EF40, as seen, the shifter window is not available as a separate part. The EF40 is a budget shifter, and normally a shifter window on a higher spec unit (XT or XTR) would be more than the complete EF40 costs