Point 145 in the category of MODALITY and ELLIPSIS is defined as:
‘ought to’ without a following verb where the previous main verb is understood.
There is an important note in the comments section of the EGP:
This is a very low-frequency form in both the learner and native speaker data.
A search for collocates up to 4 spaces to the left of
1 THEY (PPHS2 ) 210
2 THAN (CSN ) 128
3 THINK (VV0 ) 47
4 REALLY (RR ) 42
5 WAY (NN1 ) 39
*google search does not allow a search for the full stop. This makes it very hard to find examples of it.