The impeller housing mounting holes are slotted. If you loosen the mounting bolts you should be able to slide the whole housing in or out. The tension should be 10-15mm when pushed with your finger. Do not overtighten.
This should help, if you need anything else let me know.
PS here is a link to a site where you can download a service manual for your engine
Outstanding assistance with extras; thanks for the manual site!!!
No problem glad I could help
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