Hi @filicophyta
Don't know the blender, but have you tried inserting the spring and housing back in and then twisting the housing (left or right?) to see if it locks into place?
If still no good, according to p.32 of the [https://www.cuisinart.ca/on/demandware.static/-/Sites-ca-cuisinart-Library/en_CA/dw2c523905/Instruction%20Booklet/csb87c_en.pdf|user manual] there's a 3 year warranty on the product.
If the warranty period is still valid, contact the manufacturer as shown on p.33 and get it repaired or replaced under warranty.