Update Having examined it more carefully in comparison with a similar partial 14 bar strike, I am not so certain of my original hypothesis. It is probably a 14 bar but ?postally used. I have been advised to get Ted Proud's book on postmarks, make a tracing on a transparency and then superimposed to compare.
This 1888 5c stamp has a full on 14 bar chop. It would very unusual for a CTO to be placed centrally as it would be quicker to try to frank 4 stamps at a time as they were doing whole sheets. Also the stamps with postal used 14 bar on envelopes that I have seen tend to have this franking placed centrally.
This 1888 1c has 16 bars visible is probably a 17 bar cancellation. Unfortunately, no sharp ends are accessible and it is not very "eye" shaped. Perhaps those features are more typical of the 18-19 bar cancels.
This 1888 3c violet has a full on cancel with 15 bars visible is probably an 18-19 bar postally used item.
This 1886 4c stamp is again a rather faded item. There is a 13 bar oval cancel with 2 Sandakan postmarks in red even though this bar cancellation is more associated with Kudat and Elopura..
This 2c 1888 stamp is more uncertain. I was drawn by the unusual shape of what seems to be a 14 bar cancel. The bars are irregular in thickness and direction. It looks like a worn chop. Would that make it more likely that it was applied in a busy post office rather than the clean pristine appearance we tend to see with a CTO? But then it is a corner cancellation. And also with stamps of this issue, one wonders whether the stamp itself is a clever forgery with a fake cancel.
Update Anon, I think you are right. It is a Fournier probably.
A thick bar cancellation which corresponds well with the 9 bar cancel of Labuan. This stamp was probably used in Labuan. The 7 bar Mempakul cancellation is a possibility but I think the bars are thicker.