Replace Worn Rubber Cover Over Grohe Ladylux Cafe 33 755 Kitchen Sink Spray Head
Call Grohe customer service and tell them to send you a free replacement part and instructions/diagram: grohe:

Residential Products: We provide the following warranties on all GROHE products to the original purchaser, installed in a residential setting. This warranty is effective for all faucets sold after January 1, 1997.
Mechanical Warranty: A Limited Lifetime Warranty is provided on all mechanical parts to be free from manufacturing defects in materials and workmanship under normal use for as long as the original purchaser owns their home.
Finish Warranty: A Lifetime Warranty is provided on all GROHE product finishes to the original purchaser against manufacturing defects in materials and workmanship