Thanks for coming back
The decompressors on the 31 & 33 series fail very regularly
I keep seeral of the cams in stock for this reason
Do not run the engine till it is fixed as the broken bits can get jambed in the engine and do more damage
Not a bit repair but does require removing the engine so at a shop will usually have a 5 hour labour charge
So if you do not feel lke tackleing it yourself then pull the engine ans send the CLEANED engine to you nearest workshop.
A real workshop ( the ones that only do repairs & sell used mowers ) will usually do it faster, cheaper & better than a glass front new mower retailer .