All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
You do not have to repeat the entire Ghusl (ritual bath); it is sufficient for you to remove that gum and wash underneath it if water did not reach it.
The sequence (order) in Ghusl due to Janaabah (sexual defilement) is not a condition for its validity according to the view of most scholars.
For more benefit, please refer to Fatwa 308284.
Allah knows best.