Sound to me like the laser is getting weak and can’t error correct as good as it used to.
Do you have the early one (best) with the 4 square transformers? (great r2r multibit unit)
http://lampizator.eu/LAMPIZATOR/REFERENCES/SHANLING%20T100/shanlingcdt100.jpg
Laser/mech CDM-12.10
Or the later one with the three rounded transformers, not as good.
http://www.china-hifi-audio.com/images/Shanling/Shanling-T-100-MKII-hiend-CD-player-5.jpg
Laser/Mech VAM-1201
Have you tried to clean the laser? If clean, they are getting quite old now and may need to be replaced.
Cheers George