Insert the 4 COINS in the slot (I); take the MILK (J).
Return to Robert's House.
Place the MILK in the saucer (K); take the WEIGHT (K1).
Return to Russell's Office.
Use the CLOCK KEY in the clock; turn the key twice and take the BALALAIKA (L).
Return to Backstage.
Place the FAN (M) and the BALALAIKA (N) on the puppets.
Take the COMEDY MASK and the Book (O).
Place the WEIGHT (P) and the LEVER (Q) on the catapult; pull the lever. Take the PRUNERS (R).
Place the COMEDY and TRAGEDY MASKS on the back door (S) to activate a puzzle.
Place the symbols in the right spots.
Solution: 2, 2, 1, and 3.
Go through the door to enter the Dressing Room.